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How to create your own ad filters

A filter is a set of filtering rules applied to specific content, such as banners or pop-ups. AdGuard has a list of standard filters created by our team. We constantly improve and update them, striving to meet the needs of most of our users.

At the same time, AdGuard allows you to create your own custom filters using the same types of rules that we have in our filters.

To describe the syntax of our filtering rules, we use Augmented BNF for Syntax Specifications, but we do not always strictly follow this specification.

Originally, the AdGuard's syntax was based on the syntax of Adblock Plus rules. Later, we extended it with new types of rules for better ad filtering. Some parts of this article about the rules common both to AdGuard and ABP were taken from this article.

Comments​

Any line that starts with an exclamation mark is a comment. In the list of rules it is displayed in gray color. AdGuard will ignore this line, so you can write anything you want. Comments are usually placed above the rules and used to describe what a rule does.

For example:

! This is the comment. Under this line there is an actual filtering rule.
||example.org^

Examples​

Blocking by domain name​

Blocking by domain name

This rule blocks:

  • http://example.org/ad1.gif
  • http://subdomain.example.org/ad1.gif
  • https://ads.example.org:8000/

This rule does not block:

  • http://ads.example.org.us/ad1.gif
  • http://example.com/redirect/http://ads.example.org/

Blocking exact address​

Blocking exact address

This rule blocks:

  • http://example.org/

This rule does not block:

  • https://example.org/banner/img

Basic rule modifiers​

Filtering rules support numerous modifiers that allow you to fine-tune the rule behavior. Here is an example of a rule with some simple modifiers.

Basic rule modifiers

This rule blocks:

  • http://example.org/script.js if this script is loaded from example.com.

This rule does not block:

  • https://example.org/script.js if this script is loaded from example.org.
  • https://example.org/banner.png because it is not a script.

Unblocking an address​

This rule unblocks:

  • http://example.org/banner.png even if there is a blocking rule for this address.

Blocking rules with $important modifier can override exceptions.

Unblocking everything on a website​

Unblocking everything

This rule unblocks

  • It disables all cosmetic rules on example.com.
  • It unblocks all requests sent from this website even if there is are blocking rules matching these requests.

Cosmetic rule​

Cosmetic rule

Cosmetic rules are based on using a special language named CSS, which every browser understands. Basically, it adds a new CSS style to the website which purpose is to hide particular elements. You can learn more about CSS in general here.

AdGuard extends CSS and lets filters developers handle much more complicated cases. However, to use these extended rules, you need to be fluent in regular CSS.

Popular CSS selectors

NameCSS selectorDescription
ID selector#bannersMatches all elements with id attribute equal to banners.
Class selector.bannersMatches all elements with class attribute containing banners.
Attribute selectordiv[class="banners"]Matches all div elements with class attribute exactly equal to banners.
Attribute substring selectordiv[class^="advert1"]Matches all div elements which class attribute starts with the advert1 string.
Attribute substring selectordiv[class$="banners_ads"]Matches all div elements which class attribute ends with the banners_ads string.
Attribute substring selectora[href^="http://example.com/"]Matches all links that are loaded from http://example.com/ domain.
Attribute selectora[href="http://example.com/"]Matches all links to exactly the http://example.com/ address.

Restrictions​

Trusted filters​

Some rules can be used only in trusted filters. This category includes:

Basic rules​

The most simple rules are so-called Basic rules. They are used to block requests to specific URLs. Or to unblock it, if there is a special marker "@@" at the beginning of the rule. The basic principle for this type of rules is quite simple: you have to specify the address and additional parameters that limit or expand the rule scope.

Sub-requests

Basic rules for blocking requests are applied only to sub-requests. That means they will not block the loading of the page.

Response status

Browser detects a blocked request as completed with an error.

Basic rules syntax​

      rule = ["@@"] pattern [ "$" modifiers ]
modifiers = [modifier0, modifier1[, ...[, modifierN]]]
  • pattern — an address mask. Every request URL is collated to this mask. You can also use special characters in the template, their description is below. Note that AdGuard trims URLs to a length of 4096 characters in order to speed up matching and avoid issues with ridiculously long URLs.
  • @@ — a marker that is used in rules of exception. To turn off filtering for a request, start your rule with this marker.
  • modifiers — parameters that "clarify" the basic rule. Some of them limit the rule scope and some can completely change they way it works.

Special characters​

  • * — a wildcard character. It is used to represent "any set of characters". This can also be an empty string or a string of any length.
  • || — matching the beginning of an address. With this character you do not have to specify a particular protocol and subdomain in address mask. It means, || stands for http://*., https://*., ws://*., wss://*. at once.
  • ^ — a separator character mark. Separator character is any character, but a letter, a digit, or one of the following: _ - . %. In this example separator characters are shown in bold: http://example.com/?t=1&t2=t3. The end of the address is also accepted as separator.
  • | — a pointer to the beginning or the end of address. The value depends on the character placement in the mask. For example, a rule swf| corresponds to http://example.com/annoyingflash.swf , but not to http://example.com/swf/index.html. |http://example.org corresponds to http://example.org, but not to http://domain.com?url=http://example.org.

Visual representation

We also recommend to get acquainted with this article, for better understanding of how such rules should be made.

Regular expressions support​

If you want even more flexibility in making rules, you can use Regular expressions instead of a default simplified mask with special characters.

Performance

Rules with regular expressions work more slowly, therefore it is recommended to avoid them or to limit their scope to specific domains.

If you want a blocker to determine a regular expression, the pattern has to look like this:

pattern = "/" regexp "/"

For example, /banner\d+/$third-party this rule will apply the regular expression banner\d+ to all third-party requests. Exclusion rule with regular expression looks like this: @@/banner\d+/.

Compatibility with different versions of AdGuard

AdGuard Safari and AdGuard for iOS do not fully support regular expressions because of Content Blocking API restrictions (look for "The Regular expression format" section).

Wildcard support for TLD (top-level domains)​

Wildcard characters are supported for TLDs of the domains in patterns of cosmetic, HTML filtering and JavaScript rules.

For cosmetic rules, e.g. example.*##.banner, multiple domains are matched due to the part .*, i.e. example.com, sub.example.net, example.co.uk, etc.

For basic rules the described logic is applicable only for the domains specified in $domain modifier, e.g. ||*/banners/*$image,domain=example.*.

Compatibility with different versions of AdGuard

In AdGuard for Windows, Mac, Android, and AdGuard Browser extension rules with wildcard .* match any public suffix (or eTLD). But for AdGuard for Safari and iOS the supported list of top-level domains is limited due to Safari limitations.

Rules with wildcard for TLD are not supported by AdGuard Content Blocker.

Basic rules examples​

  • ||example.com/ads/* — a simple rule, which corresponds to addresses like http://example.com/ads/banner.jpg and even http://subdomain.example.com/ads/otherbanner.jpg.

  • ||example.org^$third-party — this rule blocks third-party requests to example.org and its subdomains.

  • @@||example.com$document — general exception rule. It completely disables filtering for example.com and all subdomains. There is a number of modifiers which can be used in exception rules. For more details, please follow the link below.

Basic rules modifiers​

Note

The features described in this section are intended for experienced users. They extend capabilities of "Basic rules", but in order to use them you need to have a basic understanding of the way your browser works.

You can change the behavior of a "basic rule" by using additional modifiers. Modifiers should be located in the end of the rule after a $ sign and be separated by commas.

Example:

||domain.com^$popup,third-party

Basic modifiers​

The following modifiers are the most simple and frequently used. Basically, they just limit the scope of rule application.

$app​

This modifier lets you narrow the rule coverage down to a specific application (or a list of applications). This might be not too important on Windows and Mac, but this is very important on mobile devices where some of the filtering rules must be app-specific.

  • Android — use the app package name, e.g. org.example.app.
  • Windows — use the process name, e.g. chrome.exe.
  • Mac — use the bundle ID or the process name, e.g. com.google.Chrome.

For Mac, you can find out the bundle ID or the process name of the app by viewing the respective request details in the Filtering log.

Examples

  • ||baddomain.com^$app=org.example.app — a rule to block requests that match the specified mask and are sent from the org.example.app Android app.
  • ||baddomain.com^$app=org.example.app1|org.example.app2 — the same rule but it works for both org.example.app1 and org.example.app2 apps.

If you want the rule not to be applied to certain apps, start the app name with the ~ sign.

  • ||baddomain.com^$app=~org.example.app — a rule to block requests that match the specified mask and are sent from any app save for the org.example.app.
  • ||baddomain.com^$app=~org.example.app1|~org.example.app2 — same as above, but now two apps are excluded: org.example.app1 and org.example.app2.

Compatibility with different versions of AdGuard

Only AdGuard for Windows, Mac, Android are technically capable of using rules with $app modifier.

$denyallow​

$denyallow modifier allows to avoid creating additional rules when it is needed to disable a certain rule for specific domains. $denyallow matches only target domains and not referrer domains.

Adding this modifier to a rule is equivalent to excluding the domains by the rule's matching pattern or to adding the corresponding exclusion rules. To add multiple domains to one rule, use the | character as a separator.

Restrictions

  • The rule's matching pattern cannot target any specific domains, e.g. it cannot start with ||.
  • Domains in the modifier value cannot be negated, e.g. $denyallow=~x.com, or have a wildcard TLD, e.g. $denyallow=x.*.

The rules which violate these restrictions are considered invalid.

Examples

This rule:

*$script,domain=a.com|b.com,denyallow=x.com|y.com

is equivalent to this one:

/^(?!.*(x.com|y.com)).*$/$script,domain=a.com|b.com

or to the combination of these three:

*$script,domain=a.com|b.com
@@||x.com$script,domain=a.com|b.com
@@||y.com$script,domain=a.com|b.com

Compatibility with different versions of AdGuard

Rules with $denyallow modifier are not supported by AdGuard Content Blocker.

$domain​

$domain limits the rule scope to requests made from the specified domains and their subdomains (as indicated by the Referer HTTP header). To add multiple domains to one rule, use the | character as a separator.

Examples

Just $domain:

  • ||baddomain.com^$domain=example.org blocks requests that match the specified mask, and are sent from domain example.org or its subdomains.
  • ||baddomain.com^$domain=example.org|example.com — the same rule, but it works for both example.org and example.com.

If you want the rule not to be applied to certain domains, start a domain name with ~ sign.

$domain and negation ~:

  • ||baddomain.com^$domain=~example.org blocks requests matching the pattern sent from any domain except example.org and its subdomains.
  • ||baddomain.com^$domain=example.org|~foo.example.org blocks requests sent from example.org and its subdomains, except the subdomain foo.example.org.

$domain modifier matching target domain:

In some cases the $domain modifier can match not only the referrer domain, but also the target domain. This happens when all of the following is true:

  1. The request has document content type.
  2. The rule pattern does not match any particular domains.
  3. The rule pattern does not contain regular expressions.
  4. The $domain modifier contains only excluded domains, e.g. $domain=~example.org|~example.com.

The following predicate should be satisfied to perform a target domain matching:

1 AND ((2 AND 3) OR 4)

That is, if the modifier $domain contains only excluded domains, then the rule does not need to meet the second and third conditions to match the target domain against the modifier $domain.

If some of the conditions above are not met but the rule contains $cookie or $csp modifier, the target domain will still be matched.

If the referrer matches a rule with $domain that explicitly excludes the referrer domain, then the rule will not be applied even if the target domain also matches the rule. This affects rules with $cookie and $csp modifiers, too.

Examples

  • *$cookie,domain=example.org|example.com will block cookies for all requests to and from example.org and example.com.
  • *$document,domain=example.org|example.com will block all requests to and from example.org and example.com.

In the following examples it is implied that requests are sent from http://example.org/page (the referrer) and the target URL is http://targetdomain.com/page.

  • page$domain=example.org will be matched, as it matches the referrer domain.
  • page$domain=targetdomain.com will be matched, as it matches the target domain and satisfies all requirements mentioned above.
  • ||*page$domain=targetdomain.com will not be matched, as the pattern ||*page may match specific domains, e.g. example.page.
  • ||*page$domain=targetdomain.com,cookie will be matched because the rule contains $cookie modifier despite the pattern ||*page may match specific domains.
  • /banner\d+/$domain=targetdomain.com will not be matched as it contains a regular expression.
  • page$domain=targetdomain.com|~example.org will not be matched because the referrer domain is explicitly excluded.

Limitations

Safari does not support the simultaneous use of allowed and disallowed domains, so rules like ||baddomain.com^$domain=example.org|~foo.example.org will not work in AdGuard for Safari.

Compatibility with different versions of AdGuard

Starting with CoreLibs v1.12, the $domain modifier can be alternatively spelled as $from.

$header​

The $header modifier allows matching the HTTP response having a specific header with (optionally) a specific value.

Syntax

$header "=" h_name [":" h_value]
h_value = string / regexp

where:

  • h_name — required, an HTTP header name. It is matched case-insesitively.
  • h_value — optional, an HTTP header value matching expression, it may be one of the following:
    • string — a sequence of characters. It is matched against the header value lexicographically;
    • regexp — a regular expression, starts and ends with /. The pattern works the same way as in the basic URL rules, but the characters /, $ and , must be escaped with \.

The modifier ":" h_value part may be omitted. In that case the modifier matches the header name only.

Compatibility with different versions of AdGuard

Rules with the $header modifier are supported by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.11 or later.

Examples

  • ||example.com^$header=set-cookie:foo blocks requests whose responses have the Set-Cookie header with the value matching foo literally.
  • ||example.com^$header=set-cookie blocks requests whose responses have the Set-Cookie header with any value.
  • @@||example.com^$header=set-cookie:/foo\, bar\$/ unblocks requests whose responses have the Set-Cookie header with value matching the foo, bar$ regular expression.
  • @@||example.com^$header=set-cookie unblocks requests whose responses have a Set-Cookie header with any value.

$important​

The $important modifier applied to a rule increases its priority over any other rule without $important modifier. Even over basic exception rules.

Examples

! blocking rule will block all requests despite of the exception rule
||example.org^$important
@@||example.org^
! if the exception rule also has `$important` modifier, it will prevail and requests won't be blocked
||example.org^$important
@@||example.org^$important
! if a document-level exception rule is applied to the document, the `$important` modifier will be ignored;
! so if a request to `example.org` is sent from the `test.org` domain, the blocking rule will not be applied despite it has the `$important` modifier
||example.org^$important
@@||test.org^$document

$match-case​

This modifier defines a rule which applies only to addresses that match the case. Default rules are case-insensitive.

Examples

  • */BannerAd.gif$match-case — this rule will block http://example.com/BannerAd.gif, but not http://example.com/bannerad.gif.

$method​

This modifier limits the rule scope to requests that use the specified set of HTTP methods. Negated methods are allowed. The methods must be specified in all lowercase characters, but are matched case-insensitively.

Examples

  • ||evil.com^$method=get|head blocks only GET and HEAD requests to evil.com.
  • ||evil.com^$method=~post|~put blocks any requests except POST or PUT to evil.com.

Compatibility with different versions of AdGuard

$method is available starting with CoreLibs v1.12.

AdGuard will try to close the browser tab with any address that matches a blocking rule with this modifier. Please note that not all the tabs can be closed.

Note

It may not work if the popped up page is cached by the browser.

Examples

  • ||domain.com^$popup — if you try to go to http://domain.com/ from any page in the browser, a new tab in which specified site has to be opened will be closed by this rule.

Compatibility with different versions of AdGuard

  1. $popup modifier works best in AdGuard Browser Extension.
  2. In AdGuard for Safari and iOS, $popup rules simply block the page right away.
  3. In AdGuard for Windows, Mac, and Android, $popup modifier may not detect a popup in some cases and it won't be blocked. $popup modifier applies the document content type with a special flag which is passed to a blocking page. Blocking page itself can do some checks and close the window if it is really a popup. Otherwise, page should be loaded. It can be combined with other request type modifiers, such as $third-party and $important. However, the blocking page may not detect a popup in some cases, so it is recommended to use the AdGuard Popup Blocker userscript instead.

$third-party​

A restriction of third-party and own requests. A third-party request is a request from a different domain. For example, a request to example.org from domain.com is a third-party request.

Note

To be considered as such, a third-party request should meet one of the following conditions:

  1. Its referrer is not a subdomain of the target domain or vice versa. For example, a request to subdomain.example.org from example.org is not a third-party request.
  2. Its Sec-Fetch-Site header is set to cross-site. If there is a $third-party modifier, the rule is only applied to third-party requests.

Examples

$third-party:

  • ||domain.com^$third-party — this rule applies to all domains, except domain.com and its subdomains. An example of a third-party request: http://example.org/banner.jpg.

If there is a $~third-party modifier, the rule is only applied to the requests that are not from third parties. Which means, they have to be sent from the same domain.

$~third-party:

  • ||domain.com$~third-party — this rule is applied to domain.com, but not to the other domains. Example of a request that is not a third-party request: http://domain.com/icon.ico.

$to​

$to limits the rule scope to requests made to the specified domains and their subdomains. To add multiple domains to one rule, use the | character as a separator.

Examples

  • /ads$to=evil.com|evil.org blocks any request to evil.com or evil.org and their subdomains with a path matching /ads.
  • /ads$to=~not.evil.com|evil.com blocks any request to evil.com and its subdomains, with a path matching /ads, except requests to not.evil.com and its subdomains.
  • /ads$to=~good.com|~good.org blocks any request with a path matching /ads, except requests to good.com or good.org and their subdomains.

Compatibility with other modifiers

$denyallow can not be used together with $to. It can be expressed with inverted $to: $denyallow=a.com|b.com is equivalent to $to=~a.com|~b.com.

Compatibility with different versions of AdGuard

$to is available starting with CoreLibs v1.12.

Restriction by content type​

There is a set of modifiers, which can be used to limit the rule's application area to certain type of content. These modifiers can also be combined to cover, for example, both images and scripts.

Compatibility with different versions of AdGuard

There is a big difference in how AdGuard determines the content type on different platforms. For AdGuard Browser extension, content type for every request is provided by browser. AdGuard for Windows, Mac, Android use following method: first we try to determine the type of the request by the Sec-Fetch-Dest request header or by the filename extension. If the request is not blocked at this stage, the type will be determined using the Content-Type header at the beginning of the server response.

Content type modifiers examples

  • ||example.org^$image — corresponds to all images from example.org.
  • ||example.org^$script,stylesheet — corresponds to all the scripts and styles from example.org.
  • ||example.org^$~image,~script,~stylesheet — corresponds to all requests to example.org except for the images, scripts and styles.

$document​

The rule corresponds to the main frame document requests, i.e. HTML documents that are loaded in the browser tab. It does not match iframes, there is a $subdocument modifier for these.

By default, AdGuard does not block the requests that are loaded in the browser tab (e.g. "main frame bypass"). The idea is not to prevent pages from loading as the user clearly indicated that they want this page to be loaded. However, if the $document modifier is specified explicitly, AdGuard does not use that logic and prevents the page load. Instead, it responds with a "blocking page".

If this modifier is used with an exclusion rule (@@), it completely disables blocking on corresponding pages. It is equivalent to using $elemhide, $content, $urlblock, $jsinject, and $extension modifiers simultaneously.

Examples

  • @@||example.com^$document completely disables filtering on all pages at example.com and all subdomains.

  • @@||example.com^$document,~extension completely disables blocking on any pages at example.com and all subdomains, but continues to run userscripts there.

  • ||example.com^$document blocks HTML document request to example.com with a blocking page.

  • ||example.com^$document,redirect=noopframe redirects HTML document request to example.com to an empty html document.

  • ||example.com^$document,removeparam=test removes test query parameter from HTML document request to example.com.

  • ||example.com^$document,replace=/test1/test2/ replaces test1 with test2 in HTML document request to example.com.

Compatibility with different versions of AdGuard

Blocking rules with $document modifier are not supported by AdGuard Content Blocker.

$font​

The rule corresponds to requests for fonts, e.g. .woff filename extension.

$image​

The rule corresponds to images requests.

$media​

The rule corresponds to requests for media files — music and video, e.g. .mp4 files.

$object​

The rule corresponds to browser plugins resources, e.g. Java or Flash.

$other​

The rule applies to requests for which the type has not been determined or does not match the types listed above.

$ping​

The rule corresponds to requests caused by either navigator.sendBeacon() or the ping attribute on links.

Compatibility with different versions of AdGuard

AdGuard for Windows, Mac, and Android often cannot accurately detect navigator.sendBeacon(). For reliable detection, use AdGuard Browser Extension.

$script​

The rule corresponds to script requests, e.g. javascript, vbscript.

$stylesheet​

The rule corresponds to CSS files requests.

$subdocument​

The rule corresponds to requests for built-in pages — HTML tags frame and iframe.

Examples

  • ||example.com^$subdocument blocks built-in page requests (frame and iframe) to example.com and all its subdomains anywhere.
  • ||example.com^$subdocument,domain=domain.com blocks built-in page requests (frame и iframe) to example.com (and its subdomains) from domain.com and all its subdomains.

$websocket​

The rule applies only to WebSocket connections.

Compatibility with different versions of AdGuard

$websocket modifier is supported in all AdGuard products except AdGuard Content Blocker. As for AdGuard for Safari and AdGuard for iOS, it's supported on devices with macOS Monterey (version 12) and iOS 16 or higher.

$xmlhttprequest​

The rule applies only to ajax requests (requests sent via javascript object XMLHttpRequest).

Compatibility with different versions of AdGuard

AdGuard for Windows, Mac, Android often cannot accurately detect this type and sometimes detects it as $other or $script. For reliable detection, use AdGuard Browser Extension.

$object-subrequest (deprecated)​

Deprecation notice

$object-subrequest modifier is deprecated and is no longer supported. Rules with it are considered as invalid. The rule corresponds to requests by browser plugins (it is usually Flash).

$webrtc (deprecated)​

Deprecation notice

This modifier is deprecated and is no longer supported. Rules with it are considered as invalid. If you need to suppress WebRTC, consider using the nowebrtc scriptlet.

The rule applies only to WebRTC connections.

Examples

  • ||example.com^$webrtc,domain=example.org blocks webRTC connections to example.com for example.org.
  • @@*$webrtc,domain=example.org disables the RTC wrapper for example.org.

Exception modifiers​

Exception rules disable the other basic rules for the addresses to which they correspond. They begin with a @@ mark. All the basic modifiers listed above can be applied to them and they also have a few special modifiers.

Visual representation

We recommend to get acquainted with this article, for better understanding of how exception rules should be made.

$content​

Disables HTML filtering and $replace rules on the pages that match the rule.

Examples

  • @@||example.com^$content disables all HTML filtering rules and replace rules on pages at example.com and all its subdomains.

$elemhide​

Disables any cosmetic rules on the pages matching the rule.

Examples

  • @@||example.com^$elemhide disables all cosmetic rules on pages at example.com and all subdomains.

$extension​

Disables all userscripts on the pages matching this rule.

Examples

  • @@||example.com^$extension — userscripts will not work on all pages of the example.com website.

Compatibility with different versions of AdGuard

Only AdGuard for Windows, Mac, Android are technically capable of using rules with $extension modifier.

$jsinject​

Forbids adding of javascript code to the page. You can read about javascript rules further.

Examples

  • @@||example.com^$jsinject disables javascript on pages at example.com and all subdomains.

specifichide​

Disables all specific element hiding and CSS rules, but not general ones. Has an opposite effect to $generichide.

Examples

  • @@||example.org^$specifichide disables example.org##.banner but not ##.banner.

Note

All cosmetic rules — not just specific ones — can be disabled by $elemhide modifier.

Compatibility with different versions of AdGuard

Rules with $specifichide modifier are supported by AdGuard for Windows, Mac, Android, and AdGuard Browser extension for Chrome, Firefox, Edge.

$stealth​

Disables the Stealth Mode module for all corresponding pages and requests.

Syntax

$stealth [= opt1 [| opt2 [| opt3 [...]]]]

opt(i) stand for certain Stealth Mode options disabled by the modifier. The modifier can contain any number of options (see below) or not contain them at all. In the latter case the modifier disables all the Stealth Mode features.

The list of the available modifier options:

Examples

  • @@||example.com^$stealth disables Stealth Mode for example.com (and subdomains) requests, except for blocking cookies and hiding tracking parameters (see below).
  • @@||domain.com^$script,stealth,domain=example.com disables Stealth Mode only for script requests to domain.com (and its subdomains) on example.com and all its subdomains.
  • @@||example.com^$stealth=3p-cookie|dpi disables blocking third-party cookies and DPI fooling measures for example.com.

Note

Blocking cookies and removing tracking parameters is achieved by using rules with $cookie and $removeparam modifiers. Exception rules with only $stealth modifier will not do those things. If you want to completely disable all Stealth Mode features for a given domain, you need to include all three modifiers: @@||example.org^$stealth,removeparam,cookie

Compatibility with different versions of AdGuard

  • Stealth Mode is available in AdGuard for Windows, Mac, Android, and AdGuard Browser Extension. All other products will ignore the rules with $stealth modifier.
  • $stealth modifier with specific options is supported by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.10 or later.

$urlblock​

Disables blocking of all requests sent from the pages matching the rule.

Examples

  • @@||example.com^$urlblock — any requests sent from the pages at example.com and all subdomains are not going to be blocked.

Generic rules​

Before we can proceed to the next modifiers, we have to make a definition of generic rules. The rule is generic if it is not limited to specific domains. Wildcard character * is supported as well.

For example, these rules are generic:

###banner
*###banner
#@#.adsblock
*#@#.adsblock
~domain.com###banner
||domain.com^
||domain.com^$domain=~example.com

And these are not:

domain.com###banner
||domain.com^$domain=example.com
$genericblock​

Disables generic basic rules on pages that correspond to exception rule.

Examples

  • @@||example.com^$genericblock disables generic basic rules on any pages at example.com and all subdomains.
$generichide​

Disables all generic cosmetic rules on pages that correspond to the exception rule.

Examples

  • @@||example.com^$generichide disables generic cosmetic rules on any pages at example.com and its subdomains.

Advanced capabilities​

These modifiers are able to completely change the behaviour of basic rules.

$all​

$all modifier is made of $document, $popup, and $csp modifiers. E.g. rule ||example.org^$all is converting into such a set of rules:

||example.org^$document,popup
||example.org^$csp=script-src 'self' 'unsafe-eval' http: https: data: blob: mediastream: filesystem:
||example.org^$csp=font-src 'self' 'unsafe-eval' http: https: data: blob: mediastream: filesystem:
||example.org^

$badfilter​

The rules with the $badfilter modifier disable other basic rules to which they refer. It means that the text of the disabled rule should match the text of the $badfilter rule (without the $badfilter modifier).

Examples

  • ||example.com$badfilter disables ||example.com
  • ||example.com$image,badfilter disables ||example.com$image
  • @@||example.com$badfilter disables @@||example.com
  • ||example.com$domain=domain.com,badfilter disables ||example.com$domain=domain.com

Rules with $badfilter modifier can disable other basic rules for specific domains if they fulfill the following conditions:

  1. The rule has a $domain modifier.
  2. The rule does not have a negated domain ~ in $domain modifier value.

In that case, the $badfilter rule will disable the corresponding rule for domains specified in both the $badfilter and basic rules. Please note that wildcard-TLD logic works here as well.

Examples

  • /some$domain=example.com|example.org|example.io is disabled for example.com by /some$domain=example.com,badfilter
  • /some$domain=example.com|example.org|example.io is disabled for example.com and example.org by /some$domain=example.com|example.org,badfilter
  • /some$domain=example.com|example.org and /some$domain=example.io are disabled completely by /some$domain=example.com|example.org|example.io,badfilter
  • /some$domain=example.com|example.org|example.io is disabled completely by /some$domain=example.*,badfilter
  • /some$domain=example.* is disabled for example.com and example.org by /some$domain=example.com|example.org,badfilter
  • /some$domain=example.com|example.org|example.io is NOT disabled for example.com by /some$domain=example.com|~example.org,badfilter because the value of $domain modifier contains a negated domain

Compatibility with different versions of AdGuard

Rules with $badfilter modifier are not supported by AdGuard Content Blocker.

The $cookie modifier completely changes rule behavior. Instead of blocking a request, this modifier makes AdGuard suppress or modify the Cookie and Set-Cookie headers.

Multiple rules matching a single request

In case if multiple $cookie rules match a single request, we will apply each of them one by one.

Syntax

$cookie [= name[; maxAge = seconds [; sameSite = strategy ]]]

where:

  • name — optional, string or regular expression to match cookie name.
  • seconds — number of seconds for current time to offset the expiration date of cookie.
  • strategy — string for Same-Site strategy to make cookie use.

For example,

||example.org^$cookie=NAME;maxAge=3600;sameSite=lax

every time AdGuard encounters a cookie called NAME in a request to example.org, it will do the following:

  • Set its expiration date to current time plus 3600 seconds
  • Makes the cookie use Same-Site "lax" strategy.

Escaping special characters

If regular expression name is used for matching, two characters must be escaped: comma , and dollar sign $. Use backslash \ escape each of them. For example, escaped comma looks like this: \,.

Examples

  • ||example.org^$cookie blocks all cookies set by example.org; this is an equivalent to setting maxAge=0
  • $cookie=__cfduid blocks CloudFlare cookie everywhere
  • $cookie=/__utm[a-z]/ blocks Google Analytics cookies everywhere
  • ||facebook.com^$third-party,cookie=c_user prevents Facebook from tracking you even if you are logged in

$cookie rules are not affected by regular exception rules (@@) unless it is a $document exception. In order to disable a $cookie rule, the exception rule should also have a $cookie modifier. How it works:

  • @@||example.org^$cookie unblocks all cookies set by example.org
  • @@||example.org^$cookie=concept unblocks a single cookie named concept
  • @@||example.org^$cookie=/^_ga_/ unblocks every cookie that matches the regular expression

Limitations

$cookie rules support a limited list of modifiers: $domain, $~domain, $important, $third-party, and $~third-party.

Compatibility with different versions of AdGuard

Rules with $cookie modifier are not supported by AdGuard Content Blocker, AdGuard for iOS and Safari.

$csp​

This modifier completely changes the rule behavior. If it is applied to a rule, the rule will not block the matching request. Response headers will be modified instead.

In order to use this type of rules, it is required to have the basic understanding of the Content Security Policy security layer.

For the requests matching a $csp rule, we will strengthen response security policy by enhancing the content security policy, similar to the content security policy of the $csp modifier contents. $csp rules are applied independently from any other rule type. Other basic rules have no influence on it save for document-level exceptions (see the examples section below).

Multiple rules matching a single request

In case if multiple $csp rules match a single request, we will apply each of them.

Syntax

$csp value syntax is similar to the Content Security Policy header syntax.

$csp value can be empty in the case of exception rules. See examples section below.

Limitations

  1. There are a few characters forbidden in the $csp value: ,, $.
  2. $csp rules support limited list of modifiers: $domain, $important, $subdocument.
  3. Rules with report-* directives are considered invalid.

Examples

  • ||example.org^$csp=frame-src 'none' blocks all frames on example.org and its subdomains.
  • @@||example.org/page/*$csp=frame-src 'none' disables all rules with the $csp modifier exactly matching frame-src 'none' on all the pages matching the rule pattern. For instance, the rule above.
  • @@||example.org/page/*$csp disables all the $csp rules on all the pages matching the rule pattern.
  • ||example.org^$csp=script-src 'self' 'unsafe-eval' http: https: disables inline scripts on all the pages matching the rule pattern.
  • @@||example.org^$document or @@||example.org^$urlblock disables all the $csp rules on all the pages matching the rule pattern.

Compatibility with different versions of AdGuard

Rules with $csp modifier are not supported by AdGuard Content Blocker, AdGuard for iOS and Safari.

$hls​

$hls rules modify the response of a matching request. They are intended as a convenient way to remove segments from HLS playlists (RFC 8216).

Note

The word "segment" in this document means either a "Media Segment" or a "playlist" as part of a "Master Playlist": $hls rules do not distinguish between a "Master Playlist" and a "Media Playlist".

Syntax

  • ||example.org^$hls=urlpattern removes segments whose URL matches the URL pattern urlpattern. The pattern works just like the one in basic URL rules, however, the characters /, $ and , must be escaped with \ inside urlpattern.
  • ||example.org^$hls=/regexp/options removes segments where the URL or one of the tags (for certain options, if present) is matched by the regular expression regexp. Available options are:
    • t — instead of testing the segment's URL, test each of the segment's tags against the regular expression. A segment with a matching tag is removed;
    • i — make the regular expression case-insensitive.

The characters /, $ and , must be escaped with \ inside regexp.

Exceptions

Basic URL exceptions shall not disable rules with $hls modifier. They can be disabled as described below:

  • @@||example.org^$hls disables all $hls rules for responses from URLs matching ||example.org^.
  • @@||example.org^$hls=text disables all $hls rules with the value of the $hls modifier equal to text for responses from URLs matching ||example.org^.

$hls rules can also be disabled by $document, $content and $urlblock exception rules.

Restrictions

  • $hls rules are only allowed in trusted filters
  • $hls rules are not compatible with any other modifiers except $domain, $third-party, $app, $important, $match-case, and $xmlhttprequest
  • $hls rules only apply to HLS playlists, which are UTF-8 encoded text starting with the line #EXTM3U. Any other response will not be modified by these rules
  • $hls rules do not apply if the size of the original response is more than 3 MB

Note

When multiple $hls rules match the same request, their effect is cumulative.

Examples

  • ||example.org^$hls=\/videoplayback^?*&source=dclk_video_ads removes all segments with the matching URL.
  • ||example.org^$hls=/\/videoplayback\/?\?.*\&source=dclk_video_ads/i achieves more or less the same with a regular expression instead of a URL pattern.
  • ||example.org^$hls=/#UPLYNK-SEGMENT:.*\,ad/t removes all segments which have the matching tag.

Anatomy of an HLS playlist

A quick summary of the specification:

  1. An HLS playlist is a collection of text lines.
  2. A line may be empty, a comment (starts with #), a tag (also starts with #, can only be recognized by name) or a URL.
  3. A URL line is called a "segment".
  4. Tags may apply to a single segment, i.e. the first URL line after the tag, to all segments following the tag and until the tag with the same name, or to the whole playlist.

Some points specific to the operation of $hls rules:

  1. When a segment is removed, all of the tags that apply only to that segment are also removed.
  2. When there is a tag that applies to multiple segments, and all of those segments are removed, the tag is also removed.
  3. Since there is no way to recognize different kinds of tags by syntax, we recognize all of the tags specified by the RFC, plus some non-standard tags that we have seen in the field. Any lines starting with # and not recognized as a tag are passed through without modification, and are not matched against the rules.
  4. We do not match tags that apply to the whole playlist, and $hls rules can not be used to remove them, since $hls rules are intended for removing segments. If you know what you are doing, you can use $replace rules to remove or rewrite just a single tag from the playlist.

An example of a transformation done by the rules:

Original response
#EXTM3U
#EXT-X-TARGETDURATION:10
#EXTINF,5
preroll.ts
#UPLYNK-SEGMENT:abc123,ad
#UPLYNK-KEY:aabb1122
#EXT-X-DISCONTINUITY
#EXTINF,10
01.ts
#EXTINF,10
02.ts
#UPLYNK-SEGMENT:abc123,segment
#UPLYNK-KEY:ccdd2233
#EXT-X-DISCONTINUITY
#EXTINF,10
01.ts
#EXTINF,10
02.ts
#EXT-X-ENDLIST
Applied rules
||example.org^$hls=preroll
||example.org^$hls=/#UPLYNK-SEGMENT:.*\,ad/t
Modified response
#EXTM3U
#EXT-X-TARGETDURATION:10
#UPLYNK-SEGMENT:abc123,segment
#UPLYNK-KEY:ccdd2233
#EXT-X-DISCONTINUITY
#EXTINF,10
01.ts
#EXTINF,10
02.ts
#EXT-X-ENDLIST

Compatibility with different versions of AdGuard

Rules with the $hls modifier are supported by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.10 or later.

$inline-script​

$inline-script modifier is a sort of a shortcut for $csp modifier with specific value. E.g. the rule ||example.org^$inline-script is converting into such a rule:

||example.org^$csp=script-src 'self' 'unsafe-eval' http: https: data: blob: mediastream: filesystem:

$inline-font​

$inline-font modifier is a sort of a shortcut for $csp modifier with specific value. E.g. the rule ||example.org^$inline-font is converting into such a rule:

||example.org^$csp=font-src 'self' 'unsafe-eval' http: https: data: blob: mediastream: filesystem:

$jsonprune​

$jsonprune rules modify the response to a matching request by removing JSON items that match a modified JSONPath expression. They do not modify responses which are not valid JSON documents.

In AdGuard for Windows, Mac, and Android running CoreLibs v1.11 or later, $jsonprune also supports modifying JSONP (padded JSON) documents.

Syntax

  • ||example.org^$jsonprune=expression removes items that match the modified JSONPath expression expression from the response.

Due to the way rule parsing works, the characters $ and , must be escaped with \ inside expression.

The modified JSONPath syntax has the following differences from the original:

  1. Script expressions are not supported.
  2. The supported filter expressions are:
    • ?(has <key>) — true if the current object has the specified key.
    • ?(key-eq <key> <value>) — true if the current object has the specified key, and its value is equal to the specified value.
    • ?(key-substr <key> <value>) — true if the specified value is a substring of the value of the specified key of the current object.
  3. Whitespace outside of double- or single-quoted strings has no meaning.
  4. Both double- and single-quoted strings can be used.
  5. Expressions ending with .. are not supported.
  6. Multiple array slices can be specified in square brackets.

There are various online tools that make working with JSONPath expressions more convenient:

https://www.site24x7.com/tools/jsonpath-finder-validator.html https://jsonpathfinder.com/ https://jsonpath.com/

Keep in mind, though, that all JSONPath implementations have unique features/quirks and are subtly incompatible with each other.

Exceptions

Basic URL exceptions shall not disable rules with $jsonprune modifier. They can be disabled as described below:

  • @@||example.org^$jsonprune disables all $jsonprune rules for responses from URLs matching ||example.org^.
  • @@||example.org^$jsonprune=text disable all $jsonprune rules with the value of the $jsonprune modifier equal to text for responses from URLs matching ||example.org^.

$jsonprune rules can also be disabled by $document, $content and $urlblock exception rules.

Restrictions

  • $jsonprune rules are not compatible with any other modifiers except $domain, $third-party, $app, $important, $match-case, and $xmlhttprequest.
  • $jsonprune rules do not apply if the size of the original response is more than 3 MB.

Note

When multiple $jsonprune rules match the same request, they are sorted in lexicographical order, the first rule is applied to the original response, and each of the remaining rules is applied to the result of applying the previous one.

Compatibility with different versions of AdGuard

Rules with the $jsonprune modifier are supported by AdGuard for Windows, Mac and Android, running CoreLibs version 1.10 or later.

Examples

  • ||example.org^$jsonprune=\$..[one\, "two three"] removes all occurrences of the keys "one" and "two three" anywhere in the JSON document.
Input
{
    "one": 1,
    "two": {
        "two three": 23,
        "four five": 45
    }
}
Output
{
    "two": {
        "four five": 45
    }
}
  • ||example.org^$jsonprune=\$.a[?(has ad_origin)] removes all children of a that have an ad_origin key.
Input
{
    "a": [
        {
            "ad_origin": "https://example.org",
            "b": 42
        },
        {
            "b": 1234
        }
    ]
}
Output
{
    "a": [
        {
            "b": 1234
        }
    ]
}
  • ||example.org^$jsonprune=\$.*.*[?(key-eq 'Some key' 'Some value')] removes all items that are at nesting level 3 and have a property "Some key" equal to "Some value".
Input
{
    "a": {"b": {"c": {"Some key": "Some value"}, "d": {"Some key": "Other value"}}},
    "e": {"f": [{"Some key": "Some value"}, {"Some key": "Other value"}]}
}
Output
{
    "a": {"b": {"d": {"Some key": "Other value"}}},
    "e": {"f": [{"Some key": "Other value"}]}
}

Nested JSONPath expressions

In AdGuard for Windows, Mac and Android running CoreLibs v1.11 or later, JSONPath expressions may be used as keys in filter expressions.

  • ||example.org^$jsonprune=\$.elems[?(has "\$.a.b.c")] removes all children of elems which have a property selectable by the JSONPath expression $.a.b.c.
Input
{
    "elems": [
        {
            "a": {"b": {"c": 123}},
            "k": "v"
        },
        {
            "d": {"e": {"f": 123}},
            "k1": "v1"
        }
    ]
}
Output
{
    "elems": [
        {
            "d": {"e": {"f": 123}},
            "k1": "v1"
        }
    ]
}
  • ||example.org^$jsonprune=\$.elems[?(key-eq "\$.a.b.c" "abc")] removes all children of elems which have a property selectable by the JSONPath expression $.a.b.c with a value equal to "abc".
Input
{
    "elems": [
        {
            "a": {"b": {"c": 123}},
        },
        {
            "a": {"b": {"c": "abc"}}
        }
    ]
}
Output
{
    "elems": [
        {
            "a": {"b": {"c": 123}}
        }
    ]
}

$network​

This is basically a Firewall-like rule allowing to fully block or unblock access to a specified remote address.

  1. $network rules match IP addresses only! You cannot use them to block or unblock access to a domain.
  2. To match an IPv6 address, you have to use the collapsed syntax, e.g. use [2001:4860:4860::8888]$network instead of [2001:4860:4860:0:0:0:0:8888]$network.
  3. An allowlist $network rule makes AdGuard bypass data to the matching endpoint, e.g. there will be no further filtering at all.
  4. If the IP part starts and ends with / character, it is treated as a regular expression.

We recommend to get acquainted with this article, for better understanding of regular expressions.

Examples

  • 174.129.166.49:3478^$network blocks access to 174.129.166.49:3478 (but not to 174.129.166.49:34788).
  • [2001:4860:4860::8888]:443^$network blocks access to [2001:4860:4860::8888]:443.
  • 174.129.166.49$network blocks access to 174.129.166.49:*.
  • @@174.129.166.49$network makes AdGuard bypass data to the endpoint. No other rules will be applied.
  • /.+:3[0-9]{4}/$network blocks access to any port from 30000 to 39999.
  • /8.8.8.(:?8|4)/$network blocks access to both 8.8.8.8 and 8.8.8.4.

Compatibility with different versions of AdGuard

Only AdGuard for Windows, Mac, Android are technically capable of using rules with $network modifier.

$permissions​

This modifier completely changes the rule behavior. If it is applied to a rule, the rule will not block the matching request. Response headers will be modified instead.

In order to use this type of rules, it is required to have a basic understanding of the Permissions Policy security layer.

For the requests matching a $permissions rule, AdGuard strengthens response's permissions policy by adding an additional permission policy equal to the $permissions modifier contents. $permissions rules are applied independently from any other rule type. Other basic rules have no influence on it save for document-level exceptions (see the examples section).

Multiple rules matching a single request.

In case if multiple $permissions rules match a single request, AdGuard will apply each of them.

Syntax

$permissions value syntax is similar to the Permissions-Policy header syntax with one exception: comma that separates several features MUST be escaped — see examples below. The list of the available directives is available here.

$permissions value can be empty in the case of exception rules — see examples below.

Limitations

  1. Characters forbidden in the $permissions value: $;
  2. $permissions is compatible with the limited list of modifiers: $domain, $important, and $subdocument.

Examples

  • ||example.org^$permissions=sync-xhr=() disallows synchronous XMLHttpRequest requests across example.org.
  • @@||example.org/page/*$permissions=sync-xhr=() disables all rules with the $permissions modifier exactly matching sync-xhr=() on all the pages matching the rule pattern. For instance, the rule above.
  • @@||example.org/page/*$permissions disables all the $permissions rules on all the pages matching the rule pattern.
  • $domain=example.org|example.com,permissions=oversized-images=()\, sync-script=()\, unsized-media=() disallows oversized images, synchronous scripts and unsized media features across example.org and example.com.
  • @@||example.org^$document or @@||example.org^$urlblock disables all the $permission rules on all the pages matching the rule pattern.

Compatibility with different versions of AdGuard

Rules with the $permissions modifier are supported by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.11 or later.

$redirect​

AdGuard is able to redirect web requests to a local "resource".

Syntax

AdGuard uses the same filtering rules syntax as uBlock Origin. Also, it is compatible with ABP $rewrite=abp-resource modifier.

$redirect is a modifier for the basic filtering rules so rules with this modifier support all other basic modifiers like $domain, $third-party, $script, etc.

The value of the $redirect modifier must be the name of the resource that will be used for redirection.

$redirect rules' priority is higher than the regular basic blocking rules' priority. This means that if there is a basic blocking rule (even with $important modifier), $redirect rule will prevail over it. If there is an allowlist (@@) rule matching the same URL, it will disable redirecting as well (unless the $redirect rule is also marked as $important).

Disabling $redirect rules​
  • ||example.org/script.js$script,redirect=noopjs — this rule redirects all requests to example.org/script.js to the resource named noopjs.
  • ||example.org/test.mp4$media,redirect=noopmp4-1s — this rule redirects all requests to example.org/test.mp4 to the resource named noopmp4-1s.
  • @@||example.org^$redirect will disable all $redirect rules for URLs that match ||example.org^.
  • @@||example.org^$redirect=nooptext will disable all rules with $redirect=nooptext for any request that matches ||example.org^.

More information on redirects and their usage is available on GitHub.

Compatibility with different versions of AdGuard

Rules with $redirect modifier are not supported by AdGuard Content Blocker, AdGuard for iOS and Safari.

$redirect-rule​

This is basically an alias to $redirect since it has the same "redirection" values and the logic is almost similar. The difference is that $redirect-rule is applied only in the case when the target request is blocked by a different basic rule.

Negating $redirect-rule works exactly the same way as for regular $redirect rules. Even more than that, @@||example.org^$redirect will negate both $redirect and $redirect-rule rules.

Examples

||example.org/script.js
||example.org^$redirect-rule=noopjs

In this case, only requests to example.org/script.js will be "redirected" to noopjs. All other requests to example.org will be kept intact.

Compatibility with different versions of AdGuard

Rules with $redirect-rule modifier are not supported by AdGuard Content Blocker, AdGuard for iOS and Safari.

$removeheader​

Rules with $removeheader modifier are intended to remove headers from HTTP requests and responses. The initial motivation for this rule type is to be able to get rid of the Refresh header which is often used to redirect users to an undesirable location. However, this is not the only case where this modifier can be useful.

Just like $csp, $redirect, $removeparam, and $cookie, this modifier exists independently, rules with it do not depend on the regular basic rules, i.e. regular exception or blocking rules will not affect it. By default, it only affects response headers. However, you can also change it to remove headers from HTTP requests as well.

Syntax

Basic syntax

  • ||example.org^$removeheader=header-name removes a response header called header-name
  • ||example.org^$removeheader=request:header-name removes a request header called header-name

$removeheader is case-insensitive, but we suggest always using lower case.

Negating $removeheader

This type of rules works pretty much the same way it works with $csp and $redirect modifiers.

Use @@ to negate $removeheader:

  • @@||example.org^$removeheader negates all $removeheader rules for URLs that match ||example.org^.
  • @@||example.org^$removeheader=header negates the rule with $removeheader=header for any request matching ||example.org^.

$removeheader rules can also be disabled by $document and $urlblock exception rules. But basic exception rules without modifiers will not do that. For example, @@||example.com^ will not disable $removeheader=p for requests to example.com, but @@||example.com^$urlblock will.

Multiple rules matching a single request

In case of multiple $removeheader rules matching a single request, we will apply each of them one by one.

Restrictions

  1. This type of rules can be used only in trusted filters.

  2. In order to avoid compromising the security $removeheader cannot remove headers from the list below:

  • access-control-allow-origin
  • access-control-allow-credentials
  • access-control-allow-headers
  • access-control-allow-methods
  • access-control-expose-headers
  • access-control-max-age
  • access-control-request-headers
  • access-control-request-method
  • origin
  • timing-allow-origin
  • allow
  • cross-origin-embedder-policy
  • cross-origin-opener-policy
  • cross-origin-resource-policy
  • content-security-policy
  • content-security-policy-report-only
  • expect-ct
  • feature-policy
  • origin-isolation
  • strict-transport-security
  • upgrade-insecure-requests
  • x-content-type-options
  • x-download-options
  • x-frame-options
  • x-permitted-cross-domain-policies
  • x-powered-by
  • x-xss-protection
  • public-key-pins
  • public-key-pins-report-only
  • sec-websocket-key
  • sec-websocket-extensions
  • sec-websocket-accept
  • sec-websocket-protocol
  • sec-websocket-version
  • p3p
  • sec-fetch-mode
  • sec-fetch-dest
  • sec-fetch-site
  • sec-fetch-user
  • referrer-policy
  • content-type
  • content-length
  • accept
  • accept-encoding
  • host
  • connection
  • transfer-encoding
  • upgrade
  1. $removeheader rules are not compatible with any other modifiers except $domain, $third-party, $app, $important, $match-case, and content type modifiers, e.g. $script, $stylesheet, etc. The rules which have any other modifiers are considered invalid and will be discarded.

Examples

  • ||example.org^$removeheader=refresh removes Refresh header from all HTTP responses returned by example.org and its subdomains.
  • ||example.org^$removeheader=request:x-client-data removes X-Client-Data header from all HTTP requests.
  • Next block of rules removes Refresh and Location headers from all HTTP responses returned by example.org save for requests to example.org/path/*, for which no headers will be removed:
    ||example.org^$removeheader=refresh
    ||example.org^$removeheader=location
    @@||example.org/path/$removeheader

Compatibility with different versions of AdGuard

Rules with $removeheader modifier are supported by AdGuard for Windows, Mac, and Android, and AdGuard Browser extension for Chrome, Firefox, and Edge.

$removeparam​

$queryprune is an alias of $removeparam. Since $queryprune is deprecated, avoid using it and use $removeparam instead.

Rules with $removeparam modifier are intended to strip query parameters from requests' URLs. Please note that such rules are only applied to GET, HEAD, OPTIONS, and sometimes POST requests.

$removeparam rules that do not have any content type modifiers will match only requests where content type is document.

Syntax

Basic syntax

  • $removeparam=param removes query parameter with the name param from URLs of any request, e.g. a request to http://example.com/page?param=1&another=2 will be transformed into http://example.com/page?another=2.

$removeparam basic syntax is supported starting with v1.7 of CoreLibs and v3.6 of AdGuard Browser Extension.

Regular expressions

You can also use regular expressions to match query parameters and/or their values:

  • $removeparam=/regexp/[options] — removes query parameters that matches the regexp regular expression from URLs of any request. Unlike basic syntax, it means "remove query parameters normalized to a name=value string which match the regexp regular expression". [options] here is the list of regular expression options. At the moment, the only supported option is i which makes matching case-insensitive.

$removeparam syntax for regular expressions will be supported starting with CoreLibs v1.8 and AdGuard Browser Extension v4.0. For now, use the simplified version: $removeparam=param.

Escaping special characters

Do not forget to escape special characters like ,, / and $ in the regular expressions. Use \ character for that purpose. For example, an escaped comma should look like this: \,.

Note

Regexp-type rules target both name and value of the parameter. To minimize mistakes, it is safer to start every regexp with /^ unless you specifically target parameter values.

We will try to detect and ignore unescaped $ automatically using a simple rule of thumb: It is not an options delimiter if all three are true:

  1. It looks like $/;
  2. There is another slash character / to the left of it;
  3. There is another unescaped dollar sign $ to the left of that slash character.

Remove all query parameters

Specify naked $removeparam to remove all query parameters:

  • ||example.org^$removeparam — removes all query parameters from URLs matching ||example.org^.

Inversion

Use ~ to apply inversion:

  • $removeparam=~param — removes all query parameters with the name different from param.
  • $removeparam=~/regexp/ — removes all query parameters that do not match the regexp regular expression.

Negating $removeparam

This sort of rules work pretty much the same way it works with $csp and $redirect modifiers.

Use @@ to negate $removeparam:

  • @@||example.org^$removeparam negates all $removeparam rules for URLs that match ||example.org^.
  • @@||example.org^$removeparam=param negates the rule with $removeparam=param for any request matching ||example.org^.
  • @@||example.org^$removeparam=/regexp/ negates the rule with $removeparam=/regexp/ for any request matching ||example.org^.

Multiple rules matching a single request

In the case when multiple $removeparam rules match a single request, each of them will be applied one by one.

Examples

$removeparam=/^(utm_source|utm_medium|utm_term)=/
$removeparam=/^(utm_content|utm_campaign|utm_referrer)=/
@@||example.com^$removeparam

With these rules some UTM parameters will be stripped out from any request, except that requests to example.com will not be stripped at all, e.g. http://google.com/page?utm_source=s&utm_referrer=fb.com&utm_content=img will be transformed to http://google.com/page, but http://example.com/page?utm_source=s&utm_referrer=fb.com&utm_content=img will not be affected by the blocking rule.

  • $removeparam=utm_source removes utm_source query parameter from all requests.

  • $removeparam=/utm_.*/ — removes all utm_* query parameters from URL queries of any request, e.g. a request to http://example.com/page?utm_source=test will be transformed to http://example.com/page.

  • $removeparam=/^utm_source=campaign$/ — removes utm_source query parameter with the value equal to campaign. It does not touch other utm_source parameters.

Negating one $removeparam rule and replacing it with a different rule

$removeparam=/^(gclid|yclid|fbclid)=/
@@||example.com^$removeparam=/^(gclid|yclid|fbclid)=/
||example.com^$removeparam=/^(yclid|fbclid)=/

With these rules, Google, Yandex, and Facebook Click IDs will be removed from all requests. There is one exception: Google Click ID (gclid) will not be removed from requests to example.com.

Negating $removeparam for all parameters

$removeparam=/^(utm_source|utm_medium|utm_term)=/
$removeparam=/^(utm_content|utm_campaign|utm_referrer)=/
@@||example.com^$removeparam

With these rules, specified UTM parameters will be removed from any request save for requests to example.org.

Compatibility with other modifiers

$removeparam rules are compatible with basic modifiers, content type modifiers, and with $important and $app modifiers. The rules which have any other modifiers are considered invalid and will be discarded.

Note

$removeparam rules can also be disabled by $document and $urlblock exception rules. But basic exception rules without modifiers do not do that. For example, @@||example.com^ will not disable $removeparam=p for requests to example.com, but @@||example.com^$urlblock will.

Compatibility with different versions of AdGuard​

  • Rules with $removeparam modifier are supported by AdGuard for Windows, Mac, and Android and AdGuard Browser Extension for Chrome, Firefox, and Edge.

  • POST request types are supported only by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.10 or later.

Restrictions

Rules with $removeparam modifier can be used only in trusted filters.

$replace​

This modifier completely changes the rule behavior. If it is applied, the rule will not block the request. The response is going to be modified instead.

You will need some knowledge of regular expressions to use $replace modifier.

Features

  • $replace rules apply to any text response, but will not apply to binary (media, image, object, etc).
  • $replace rules do not apply if the size of the original response is more than 3MB.
  • $replace rules have a higher priority than other basic rules (including exception rules). So if a request corresponds to two different rules one of which has the $replace modifier, this rule will be applied.
  • Document-level exception rules with $content or $document modifiers do disable $replace rules for requests matching them.
  • Other document-level exception rules ($generichide, $elemhide or $jsinject modifiers) are applied alongside $replace rules. It means that you can modify the page content with a $replace rule and disable cosmetic rules there at the same time.

$replace value can be empty in the case of exception rules. See examples section for further information.

Multiple rules matching a single request

In case if multiple $replace rules match a single request, we will apply each of them. The order is defined alphabetically.

Syntax

In general, $replace syntax is similar to replacement with regular expressions in Perl.

replace = "/" regexp "/" replacement "/" modifiers
  • regexp — a regular expression.
  • replacement — a string that will be used to replace the string corresponding to regexp.
  • modifiers — a regular expression flags. For example, i — insensitive search, or s — single-line mode.

In the $replace value, two characters must be escaped: comma , and dollar sign $. Use backslash \ for it. For example, an escaped comma looks like this: \,.

Examples

||example.org^$replace=/(<VAST[\s\S]*?>)[\s\S]*<\/VAST>/\$1<\/VAST>/i

There are three parts in this rule:

  • regexp - (<VAST(.|\s)*?>)(.|\s)*<\/VAST>;
  • replacement — \$1<\/VAST> where $ is escaped;
  • modifiers — i for insensitive search.

You can see how this rule works here: http://regexr.com/3cesk

Multiple $replace rules

  1. ||example.org^$replace=/X/Y/
  2. ||example.org^$replace=/Z/Y/
  3. @@||example.org/page/*$replace=/Z/Y/
  • Both rule 1 and 2 will be applied to all requests sent to example.org.
  • Rule 2 is disabled for requests matching ||example.org/page/, but rule 1 still works!

Disabling $replace rules

  • @@||example.org^$replace will disable all $replace rules matching ||example.org^.
  • @@||example.org^$document or @@||example.org^$content will disable all $replace rules originated from pages of example.org including the page itself.

Compatibility with different versions of AdGuard

Rules with $replace modifier are supported by AdGuard for Windows, Mac, and Android and AdGuard Browser Extension for Firefox. Such rules do not work in extensions for other browsers because they are unable to modify content on the network level.

Restrictions

Rules with $replace modifier can be used only in trusted filters.

noop​

noop modifier does nothing and can be used solely to increase rules' readability. It consists of a sequence of underscore characters (_) of any length and can appear in a rule as many times as needed.

Examples

||example.com$_,removeparam=/^ss\\$/,_,image
||example.com$replace=/bad/good/,___,~third-party

Compatibility with different versions of AdGuard

Rules with noop modifier are not supported by AdGuard Content Blocker.

$empty (deprecated)​

Deprecation notice

This modifier is deprecated in favor of the $redirect modifier. Rules with $empty are converting into $redirect=nooptext now.

Usually, blocked requests look like a server error to browser. If you use $empty modifier, AdGuard will emulate a blank response from the server with 200 OK status.

Examples

  • ||example.org^$empty returns an empty response to all requests to example.org and all subdomains.

Compatibility with different versions of AdGuard

Rules with $empty modifier are not supported by AdGuard Content Blocker, AdGuard for iOS and Safari.

$mp4 (deprecated)​

Deprecation notice

This modifier is deprecated in favor of the $redirect modifier. Rules with $mp4 are converting into $redirect=noopmp4-1s,media now.

As a response to blocked request AdGuard returns a short video placeholder.

Examples

  • ||example.com/videos/$mp4 blocks all video downloads from ||example.com/videos/* and changes the response to a video placeholder.

Compatibility with different versions of AdGuard

Rules with $mp4 modifier are not supported by AdGuard Content Blocker, AdGuard for iOS and Safari.

Non-basic rules

However, the capabilities of the basic rules may not be sufficient to block ads. Sometimes you need to hide an element or change part of the HTML code of a web page without breaking anything. The rules described in this section are created specifically for this purpose.

Cosmetic rules​

Work with non-basic rules requires the basic knowledge of HTML and CSS. So, if you want to learn how to make such rules, we recommend to get acquainted with this documentation.

Element hiding rules​

Element hiding rules are used to hide the elements of web pages. It is similar to applying { display: none; } style to selected element.

Element hiding rules may operate differently depending on the platform.

Syntax​

   rule = [domains] "##" selector
domains = [domain0, domain1[, ...[, domainN]]]
  • selector — CSS selector, defines the elements to be hidden.
  • domains — domain restriction for the rule.

If you want to limit the rule application area to certain domains, just enter them separated with commas. For example: example.org,example.com##selector.

This rule will be also applied to all subdomains of example.org and example.com.

If you want the rule not to be applied to certain domains, start a domain name with ~ sign. For example: ~example.org##selector.

You can use both approaches in a single rule. For example, example.org,~subdomain.example.org##domain will work for example.org and all subdomains, except subdomain.example.org.

Note

Element hiding rules are not dependent on each other. If there is a rule example.org##selector in the filter and you add ~example.org##selector both rules will be applied independently.

Examples

  • example.com##div.textad — hides a div with a class textad at example.com and all subdomains.
  • example.com,example.org###adblock — hides an element with attribute id equals adblock at example.com, example.org and all subdomains.
  • ~example.com##.textad — hides an element with a class textad at all domains, except example.com and its subdomains.

Limitations

Safari does not support both permitted and restricted domains. So the rules like example.org,~foo.example.org##.textad are invalid in AdGuard for Safari.

Exceptions

Exceptions can disable some rules on particular domains. They are very similar to usual exception rules, but instead of ## you have to use #@#.

For example, there is a rule in filter:

##.textad

If you want to disable it for example.com, you can create an exception rule:

example.com#@#.textad

Sometimes, it may be necessary to disable all restriction rules. For example, to conduct tests. To do this, use the exclusion rule without specifying a domain. It will completely disable matching CSS elemhide rule on ALL domains:

#@#.textad

The same can be achieved by adding this rule:

*#@#.textad

We recommend to use this kind of exceptions only if it is not possible to change the hiding rule itself. In other cases it is better to change the original rule, using domain restrictions.

CSS rules​

Sometimes, simple hiding of an element is not enough to deal with advertising. For example, blocking an advertising element can just break the page layout. In this case AdGuard can use rules that are much more flexible than hiding rules. With this rules you can basically add any CSS styles to the page.

Restrictions

Styles that lead to loading any resource are forbidden. Basically, it means that you cannot use any <url> type of value in the style.

Compatibility with different versions of AdGuard

CSS rules are not supported by AdGuard Content Blocker.

CSS rules may operate differently depending on the platform.

Syntax

   rule = [domains] "#$#" selector "{" style "}"
domains = [domain0, domain1[, ...[, domainN]]]
  • selector — CSS selector, that defines the elements we want to apply the style to.
  • domains — domain restriction for the rule. Same principles as in element hiding rules.
  • style — CSS style, that we want to apply to selected elements.

Examples

example.com#$#body { background-color: #333!important; }

This rule will apply a style background-color: #333!important; to the body element at example.com and all subdomains.

Exceptions

Just like with element hiding, there is a type of rules that disable the selected CSS style rule for particular domains. Exception rules syntax is almost the same, you just have to change #$# to #@$#.

For example, there is a rule in filter:

#$#.textad { visibility: hidden; }

If you want to disable it for example.com, you can create an exception rule:

example.com#@$#.textad { visibility: hidden; }

We recommend to use this kind of exceptions only if it is not possible to change the CSS rule itself. In other cases it is better to change the original rule, using domain restrictions.

Extended CSS selectors​

CSS 3.0 is not always enough to block ads. To solve this problem AdGuard extends CSS capabilities by adding support for the new pseudo-elements. We have developed a separate open-source library for non-standard element selecting and applying CSS styles with extended properties.

The idea of extended capabilities is an opportunity to match DOM elements with selectors based on their own representation (style, text content, etc.) or relations with other elements. There is also an opportunity to apply styles with non-standard CSS properties.

Application area

Extended selectors can be used in any cosmetic rule, whether they are element hiding rules or CSS rules.

Compatibility with different versions of AdGuard

Rules with extended CSS selectors are not supported by AdGuard Content Blocker.

Syntax

Regardless of the CSS pseudo-classes you are using in the rule, you can use special markers to force applying these rules by ExtendedCss. It is recommended to use these markers for all extended CSS cosmetic rules so that it was easier to find them.

The syntax for extended CSS rules:

  • #?# — for element hiding, #@?# — for exceptions
  • #$?# — for CSS rules, #@$?# — for exceptions

We strongly recommend using these markers any time when you use an extended CSS selector.

Examples

  • example.org#?#div:has(> a[target="_blank"][rel="nofollow"]) — this rule blocks all div elements containing a child node that has a link with the attributes [target="_blank"][rel="nofollow"]. The rule applies only to example.org and its subdomains.
  • example.com#$?#h3:contains(cookies) { display: none!important; } — this rule sets the style display: none!important to all h3 elements that contain the word cookies. The rule applies only to example.com and all its subdomains.
  • example.net#?#.banner:matches-css(width: 360px) — this rule blocks all .banner elements with the style property width: 360px. The rule applies only to example.net and its subdomains.
  • example.net#@?#.banner:matches-css(width: 360px) — this rule will disable the previous rule.

You can apply standard CSS selectors using the ExtendedCss library by using a rule marker #?#, e.g. #?#div.banner.

Learn more about how to debug extended selectors.

Note

Some pseudo-classes do not require selector before it. Still adding a universal selector * makes an extended selector easier to read, even though it has no effect on the matching behavior. So selector #block :has(> .inner) works exactly like #block *:has(> .inner) but second one is more obvious.

Pseudo-class names are case-insensitive, e.g. :HAS() works as :has(). Still the lower-case names are used commonly.

ExtendedCss Limitations​

  1. CSS comments and at-rules are not supported.

  2. Specific pseudo-class may have its own limitations: :has(), :xpath(), :nth-ancestor(), :upward(), :is(), :not(), and :remove().

Pseudo-class :has()​

Draft CSS 4.0 specification describes the :has() pseudo-class. Unfortunately, it is not yet supported by all popular browsers.

Note

Rules with the :has() pseudo-class should use the native implementation of :has() if they use ## marker and if it is possible, i.e. with no other extended selectors inside. To force applying of ExtendedCss rules with :has(), use #?#/#$?# marker explicitly.

Compatibility with other pseudo-classes

Synonyms :-abp-has() is supported by ExtendedCss for better compatibility.

Deprecation notice

:if() is no longer supported as a synonym for :has().

Syntax

[target]:has(selector)
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • selector — required, standard or extended CSS selector

The pseudo-class :has() selects the target elements that fit to the selector. Also the selector can start with a combinator.

A selector list can be set in selector as well. In this case all selectors in the list are being matched for now. In the future it will be fixed for <forgiving-relative-selector-list> as argument.

:has() limitations​

Usage of the :has() pseudo-class is restricted for some cases (2, 3):

  • disallow :has() inside the pseudos accepting only compound selectors;
  • disallow :has() after regular pseudo-elements.

Native :has() pseudo-class does not allow :has(), :is(), :where() inside :has() argument to avoid increasing the :has() invalidation complexity (case 1). But ExtendedCss did not have such limitation earlier and filter lists already contain such rules, so we have not added this limitation to ExtendedCss and allow to use :has() inside :has() as it was possible before. To use it, just force ExtendedCss usage by setting #?#/#$?# rule marker.

Native implementation does not allow any usage of :scope inside :has() argument ([1], [2]). Still, there are some such rules in filter lists: div:has(:scope > a) which we continue to support by simply converting them to div:has(> a), as it used to be done previously.

Examples

div:has(.banner) selects all div elements which include an element with the banner class:

<!-- HTML code -->
<div>Not selected</div>
<div>Selected
  <span class="banner">inner element</span>
</div>

div:has(> .banner) selects all div elements which include an banner class element as a direct child of div:

<!-- HTML code -->
<div>Not selected</div>
<div>Selected
  <p class="banner">child element</p>
</div>

div:has(+ .banner) selects all div elements preceding banner class element which immediately follows the div and both are children of the same parent:

<!-- HTML code -->
<div>Not selected</div>
<div>Selected</div>
<p class="banner">adjacent sibling</p>
<span>Not selected</span>

div:has(~ .banner) selects all div elements preceding banner class element which follows the div but not necessarily immediately and both are children of the same parent:

<!-- HTML code -->
<div>Not selected</div>
<div>Selected</div>
<span>Not selected</span>
<p class="banner">general sibling</p>

div:has(span, .banner) selects all div elements which include both span element and banner class element:

<!-- HTML code -->
<div>Not selected</div>
<div>Selected
  <span>child span</span>
  <p class="banner">child .banner</p>
</div>

Compatibility with old syntax

Backward compatible syntax for :has() is supported but not recommended.

Pseudo-class :contains()​

The :contains() pseudo-class principle is very simple: it allows to select the elements that contain specified text or which content matches a specified regular expression. Regexp flags are supported.

Note

The :contains() pseudo-class uses the textContent element property for matching, not the innerHTML.

Compatibility with other pseudo-classes

Synonyms :-abp-contains() and :has-text() are supported for better compatibility.

Syntax

[target]:contains(match)
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • match — required, string or regular expression for matching element textContent. Regular expression flags are supported.

Examples

For such DOM:

<!-- HTML code -->
<div>Not selected</div>
<div id="match">Selected as IT contains "banner"</div>
<div>Not selected <div class="banner"></div></div>

the element div#match can be selected by any on these extended selectors:

! plain text
div:contains(banner)

! regular expression
div:contains(/as .* banner/)

! regular expression with flags
div:contains(/it .* banner/gi)

Note

Only the div with id=match is selected because the next element does not contain any text, and banner is a part of code, not a text.

Compatibility with old syntax

Backward compatible syntax for :contains() is supported but not recommended.

Pseudo-class :matches-css()​

The :matches-css() pseudo-class allows to match the element by its current style properties. The work of the pseudo-class is based on using the Window.getComputedStyle() method.

Syntax

[target]:matches-css([pseudo-element, ] property: pattern)
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • pseudo-element — optional, valid standard pseudo-element, e.g. before, after, first-line, etc.
  • property — required, a name of CSS property to check the element for
  • pattern — required, a value pattern that is using the same simple wildcard matching as in the basic url filtering rules OR a regular expression. For this type of matching, AdGuard always does matching in a case-insensitive manner. In the case of a regular expression, the pattern looks like /regexp/.

Special characters escaping and unescaping

For non-regexp patterns (,),[,] must be unescaped, e.g. :matches-css(background-image:url(data:*)).

For regexp patterns \ should be escaped, e.g. :matches-css(background-image: /^url\\("data:image\\/gif;base64.+/).

Restrictions

Regexp patterns do not support flags.

Examples

For such DOM:

<!-- HTML code -->
<style type="text/css">
    #matched::before {
        content: "Block me"
    }
</style>
<div id="matched"></div>
<div id="not-matched"></div>

the div elements with pseudo-element ::before and with specified content property can be selected by any of these extended selectors:

! string pattern
div:matches-css(before, content: block me)

! string pattern with wildcard
div:matches-css(before, content: block*)

! regular expression pattern
div:matches-css(before, content: /block me/)

Compatibility with other pseudo-classes

Obsolete pseudo-classes :matches-css-before() and :matches-css-after() are no longer recommended but still are supported for better compatibility.

Compatibility with old syntax

Backward compatible syntax for :matches-css() is supported but not recommended.

Pseudo-class :matches-attr()​

The :matches-attr() pseudo-class allows to select an element by its attributes, especially if they are randomized.

Syntax

[target]:matches-attr("name"[="value"])
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • name — required, simple string or string with wildcard or regular expression for attribute name matching
  • value — optional, simple string or string with wildcard or regular expression for attribute value matching

Escaping special characters

For regexp patterns " and \ should be escaped, e.g. div:matches-attr(class=/[\\w]{5}/).

Restrictions

Regexp patterns do not support flags.

Examples

div:matches-attr("ad-link") selects the element div#target1:

<!-- HTML code -->
<div id="target1" ad-link="1random23-banner_240x400"></div>

div:matches-attr("data-*"="adBanner") selects the element div#target2:

<!-- HTML code -->
<div id="target2" data-1random23="adBanner"></div>

div:matches-attr(*unit*=/^click$/) selects the element div#target3:

<!-- HTML code -->
<div id="target3" random123-unit094="click"></div>

*:matches-attr("/.{5,}delay$/"="/^[0-9]*$/") selects the element #target4:

<!-- HTML code -->
<div>
  <inner-random23 id="target4" nt4f5be90delay="1000"></inner-random23>
</div>

Pseudo-class :matches-property()​

The :matches-property() pseudo-class allows to select an element by matching its properties.

Syntax

[target]:matches-property("name"[="value"])
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • name — required, simple string or string with wildcard or regular expression for element property name matching
  • value — optional, simple string or string with wildcard or regular expression for element property value matching

Escaping special characters

For regexp patterns " and \ should be escaped, e.g. div:matches-property(prop=/[\\w]{4}/).

Note

Regexp patterns are supported in name for any property in chain, e.g. prop./^unit[\\d]{4}$/.type.

Restrictions

Regexp patterns do not support flags.

Examples

An element with such properties:

divProperties = {
  id: 1,
  check: {
    track: true,
    unit_2random1: true,
  },
  memoizedProps: {
    key: null,
    tag: 12,
    _owner: {
      effectTag: 1,
      src: 'ad.com',
    },
  },
};

can be selected by any of these extended selectors:

div:matches-property(check.track)

div:matches-property("check./^unit_.{4,8}$/")

div:matches-property("check.unit_*"=true)

div:matches-property(memoizedProps.key="null")

div:matches-property(memoizedProps._owner.src=/ad/)

For filters maintainers:

To check properties of a specific element, do the following:

  1. Inspect the page element or select it in Elements tab of browser DevTools.
  2. Run console.dir($0) in Console tab.

Pseudo-class :xpath()​

The :xpath() pseudo-class allows to select an element by evaluating an XPath expression.

Syntax

[target]:xpath(expression)
  • target- optional, standard or extended CSS selector
  • expression — required, valid XPath expression
:xpath() limitations​

target can be omitted so it is optional. For any other pseudo-class that would mean "apply to all DOM nodes", but in case of :xpath() it just means "apply to the whole document", and such applying slows elements selecting significantly. That's why rules like #?#:xpath(expression) are limited to looking inside the body tag. For example, rule #?#:xpath(//div[@data-st-area=\'Advert\']) is parsed as #?#body:xpath(//div[@data-st-area=\'Advert\']).

Extended selectors with defined target as any selector — *:xpath(expression) — can still be used but it is not recommended, so target should be specified instead.

Works properly only at the end of selector, except for pseudo-class :remove().

Examples

:xpath(//*[@class="banner"]) selects the element div#target1:

<!-- HTML code -->
<div id="target1" class="banner"></div>

:xpath(//*[@class="inner"]/..) selects the element div#target2:

<!-- HTML code -->
<div id="target2">
  <div class="inner"></div>
</div>

Pseudo-class :nth-ancestor()​

The :nth-ancestor() pseudo-class allows to lookup the nth ancestor relative to the previously selected element.

subject:nth-ancestor(n)
  • subject — required, standard or extended CSS selector
  • n — required, number >= 1 and < 256, distance to the needed ancestor from the element selected by subject

Syntax

subject:nth-ancestor(n)
  • subject — required, standard or extended CSS selector
  • n — required, number >= 1 and < 256, distance to the needed ancestor from the element selected by subject
:nth-ancestor() limitations​

The :nth-ancestor() pseudo-class is not supported inside the argument of the :not() pseudo-class.

Examples

For such DOM:

<!-- HTML code -->
<div id="target1">
  <div class="child"></div>

  <div id="target2">
    <div>
      <div>
        <div class="inner"></div>
      </div>
    </div>
  </div>
</div>

.child:nth-ancestor(1) selects the element div#target1, div[class="inner"]:nth-ancestor(3) selects the element div#target2.

Pseudo-class :upward()​

The :upward() pseudo-class allows to lookup the ancestor relative to the previously selected element.

Syntax

subject:upward(ancestor)
  • subject — required, standard or extended CSS selector
  • ancestor — required, specification for the ancestor of the element selected by subject, can be set as:
    • number >= 1 and < 256 for distance to the needed ancestor, same as :nth-ancestor()
    • standard CSS selector for matching closest ancestor
:upward() limitations​

The :upward() pseudo-class is not supported inside the argument of the :not() pseudo-class.

Examples

For such DOM:

<!-- HTML code -->
<div id="target1" data="true">
  <div class="child"></div>

  <div id="target2">
    <div>
      <div>
        <div class="inner"></div>
      </div>
    </div>
  </div>
</div>

.inner:upward(div[data]) selects the element div#target1, .inner:upward(div[id]) selects the element div#target2, .child:upward(1) selects the element div#target1, .inner:upward(3) selects the element div#target2.

Pseudo-class :remove() and pseudo-property remove​

Sometimes, it is necessary to remove a matching element instead of hiding it or applying custom styles. In order to do it, you can use the :remove() pseudo-class as well as the remove pseudo-property.

Pseudo-class :remove() can be placed only at the end of a selector.

Syntax

! pseudo-class
selector:remove()

! pseudo-property
selector { remove: true; }
  • selector — required, standard or extended CSS selector
:remove() and remove limitations​

The :remove() pseudo-class is limited to work properly only at the end of selector.

For applying the :remove() pseudo-class to any element, a universal selector * should be used. Otherwise such extended selector may be considered as invalid, e.g. .banner > :remove() is not valid for removing any child element of banner class element, so it should look like .banner > *:remove().

If the :remove() pseudo-class or the remove pseudo-property is used, all style properties are ignored except for the debug pseudo-property.

Examples

div.banner:remove()
div:has(> div[ad-attr]):remove()

div:contains(advertisement) { remove: true; }
div[class]:has(> a > img) { remove: true; }

Note

Rules with the remove pseudo-property should use #$?# marker: $ for CSS style rules syntax, ? for ExtendedCss syntax.

Pseudo-class :is()​

The :is() pseudo-class allows to match any element that can be selected by any of selectors passed to it. Invalid selectors are skipped and the pseudo-class deals with valid ones with no error thrown. Our implementation of the native :is() pseudo-class.

Syntax

[target]:is(selectors)
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • selectors — forgiving selector list of standard or extended selectors. For extended selectors only compound selectors are supported, not complex.
:is() limitations​

Rules with the :is() pseudo-class should use the native implementation of :is() if rules use ## marker and it is possible, i.e. with no other extended selectors inside. To force applying ExtendedCss rules with :is(), use #?#/#$?# marker explicitly.

If the :is() pseudo-class argument selectors is an extended selector, due to the way how the :is() pseudo-class is implemented in ExtendedCss v2.0, it is impossible to apply it to the top DOM node which is html, i.e. #?#html:is(<extended-selectors>) does not work. So if target is not defined or defined as a universal selector *, the extended pseudo-class applying is limited to html's children, e.g. rules #?#:is(...) and #?#*:is(...) are parsed as #?#html *:is(...). Please note that there is no such limitation for a standard selector argument, i.e. #?#html:is(.locked) works fine.

Complex selectors with extended pseudo-classes are not supported as selectors argument for :is() pseudo-class, only compound ones are allowed. Check examples below for more details.

Examples

#container *:is(.inner, .footer) selects only the element div#target1:

<!-- HTML code -->
<div id="container">
  <div data="true">
    <div>
      <div id="target1" class="inner"></div>
    </div>
  </div>
</div>

Due to limitations :is(*:not([class]) > .banner)' does not work but :is(*:not([class]):has(> .banner)) can be used instead of it to select the element div#target2:

<!-- HTML code -->
<span class="span">text</span>
<div id="target2">
  <p class="banner">inner paragraph</p>
</div>

Pseudo-class :not()​

The :not() pseudo-class allows to select elements which are not matched by selectors passed as argument. Invalid argument selectors are not allowed and error is to be thrown. Our implementation of the :not() pseudo-class.

Syntax

[target]:not(selectors)
  • target — optional, standard or extended CSS selector, can be missed for checking any element
  • selectors — list of standard or extended selectors
:not() limitations​

Rules with the :not() pseudo-class should use the native implementation of :not() if rules use ## marker and it is possible, i.e. with no other extended selectors inside. To force applying ExtendedCss rules with :not(), use #?#/#$?# marker explicitly.

If the :not() pseudo-class argument selectors is an extended selector, due to the way how the :not() pseudo-class is implemented in ExtendedCss v2.0, it is impossible to apply it to the top DOM node which is html, i.e. #?#html:not(<extended-selectors>) does not work. So if target is not defined or defined as a universal selector *, the extended pseudo-class applying is limited to html's children, e.g. rules #?#:not(...) and #?#*:not(...) are parsed as #?#html *:not(...). Please note that there is no such limitation for a standard selector argument, i.e. #?#html:not(.locked) works fine.

The :not() is considered as a standard CSS pseudo-class inside the argument of the :upward() pseudo-class because :upward() supports only standard selectors.

"Up-looking" pseudo-classes which are :nth-ancestor() and :upward() are not supported inside selectors argument for :not() pseudo-class.

Examples

#container > *:not(h2, .text) selects only the element div#target1:

<!-- HTML code -->
<div id="container">
  <h2>Header</h2>
  <div id="target1"></div>
  <span class="text">text</span>
</div>

Pseudo-class :if-not() (deprecated)​

Deprecation notice

The :if-not() pseudo-class is deprecated and is no longer supported. Rules with it are considered as invalid.

This pseudo-class was basically a shortcut for :not(:has()). It was supported by ExtendedCss for better compatibility with some filters subscriptions.

Cosmetic rules priority​

The way element hiding and CSS rules are applied is platform-specific.

In AdGuard for Windows, Mac, and Android, we use a stylesheet injected into the page. The priority of cosmetic rules is the same as any other websites' CSS stylesheet. But there is a limitation: element hiding and CSS rules cannot override inline styles. In such cases, it is recommended to use extended selectors or HTML filtering.

In AdGuard Browser extension, the so called "user stylesheets" are used. They have higher priority than even the inline styles.

Extended CSS selectors use JavaScript to work and basically add an inline style themselves, therefore they can override any style.

HTML filtering rules​

In most cases, the basis and cosmetic rules are enough to filter ads. But sometimes it is necessary to change the HTML-code of the page itself before it is loaded. This is when you need filtering rules for HTML content. They allow to indicate the HTML elements to be cut out before the browser loads the page.

Compatibility with different versions of AdGuard

HTML filtering rules are supported by AdGuard for Windows, Mac, Android, and AdGuard Browser extension for Firefox. Such rules do not work in extensions for other browsers because they are unable to modify content on network level.

Syntax

      rule = [domains] "$$" tagName [attributes]
   domains = [domain0, domain1[, ...[, domainN]]]
attributes = "[" name0 = value0 "]" "[" name1 = value2 "]" ... "[" nameN = valueN "]"
  • tagName — name of the element in lower case, for example, div or script.
  • domains — domain restriction for the rule. Same principles as in element hiding rules syntax.
  • attributes — a list of attributes, that limit the elements selection. name — attribute name, value — substring, that is contained in attribute value.

Examples

HTML code:

<script data-src="/banner.js"></script>

Rule:

example.org$$script[data-src="banner"]

This rule removes all script elements with the attribute data-src containing the substring banner. The rule applies only to example.org and all its subdomains.

Special attributes

In addition to usual attributes, which value is every element checked for, there is a set of special attributes that change the way a rule works. Below there is a list of these attributes:

  • tag-content

This is the most frequently used special attribute. It limits selection with those elements whose innerHTML code contains the specified substring.

You should use "" to escape ", for instance: $$script[tag-content="alert(""this is ad"")"]

For example, take a look at this HTML code:

<script type="text/javascript">
    document.write('<div>banner text</div>" />');
</script>

Following rule will delete all script elements with a banner substring in their code:

$$script[tag-content="banner"]

Nested elements

If we are dealing with multiple nested elements and they all fall within the same HTML filtering rule, they all are going to be deleted.

  • wildcard

This special attribute works almost like tag-content and allows you to check the innerHTML code of the document. Rule will check if HTML code of the element fits to the search pattern.

You should use "" to escape ", for instance: $$script[wildcard=""banner""]

For example: $$script[wildcard="*banner*text*"]

It will check, if the code of element contains two consecutive substrings banner and text.

  • max-length

Specifies the maximum length for content of HTML element. If this parameter is set and the content length exceeds the value, a rule does not apply to the element.

Default value

If this parameter is not specified, the max-length is considered to be 8192.

For example:

$$div[tag-content="banner"][max-length="400"]

This rule will remove all the div elements, whose code contains the substring banner and the length of which does not exceed 400 characters.

  • min-length

Specifies the minimum length for content of HTML element. If this parameter is set and the content length is less than preset value, a rule does not apply to the element.

For example:

$$div[tag-content="banner"][min-length="400"]

This rule will remove all the div elements, whose code contains the substring banner and the length of which exceeds 400 characters.

Exceptions

Similar to hiding rules, there is a special type of rules that disable the selected HTML filtering rule for particular domains. The syntax is the same, you just have to change $$ to $@$.

For example, there is a rule in filter:

$$script[tag-content="banner"]

If you want to disable it for example.com, you can create an exception rule:

example.com$@$script[tag-content="banner"]

Sometimes, it may be necessary to disable all restriction rules. For example, to conduct tests. To do this, use the exclusion rule without specifying a domain.

$@$script[tag-content="banner"]

We recommend to use this kind of exceptions only if it is not possible to change the hiding rule itself. In other cases it is better to change the original rule, using domain restrictions.

JavaScript rules​

AdGuard supports a special type of rules that allows you to inject any javascript code to websites pages.

Restrictions

JavaScript rules can be used only in trusted filters.

Compatibility with different versions of AdGuard

JavaScript rules are not supported by AdGuard Content Blocker.

We strongly recommend using scriptlets instead of JavaScript rules whenever possible. JS rules are supposed to help with debugging, but as a long-time solution a scriptlet rule should be used.

Syntax

rule = [domains]  "#%#" script
  • domains — domain restriction for the rule. Same principles as in element hiding rules.
  • script — arbitrary javascript code in one string.

Examples

  • example.org#%#window.__gaq = undefined; executes the code window.__gaq = undefined; on all pages at example.org and all subdomains.

Exceptions

Similar to hiding rules, there is a special type of rules that disable the selected javascript rule for particular domains. The syntax is the same, you just have to change #%# to #@%#.

For example, there is a rule in filter:

#%#window.__gaq = undefined;

If you want to disable it for example.com, you can create an exception rule:

example.com#@%#window.__gaq = undefined;

Sometimes, it may be necessary to disable all restriction rules. For example, to conduct tests. To do this, use the exclusion rule without specifying a domain.

#@%#window.__gaq = undefined;

We recommend to use this kind of exceptions only if it is not possible to change the hiding rule itself. In other cases it is better to change the original rule, using domain restrictions.

Scriptlet rules​

Scriptlet is a JavaScript function that provides extended capabilities for content blocking. These functions can be used in a declarative manner in AdGuard filtering rules.

Restrictions

Trusted scriptlets rules can be used only in trusted filters.

Note

AdGuard supports a lot of different scriptlets. In order to achieve cross-blocker compatibility, we also support syntax of uBO and ABP.

Syntax

rule = [domains]  "#%#//scriptlet(" scriptletName arguments ")"
  • scriptletName — required, a name of the scriptlet from AdGuard's Scriptlets library
  • arguments — optional, a list of string arguments (no other types of arguments are supported)

Examples

example.org#%#//scriptlet("abort-on-property-read", "alert")

This rule will be applied to example.org and subdomains pages and will execute the abort-on-property-read scriptlet with the alert parameter.

Learn more about how to debug scriptlets.

More information about scriptlets can be found on GitHub.

Compatibility with different versions of AdGuard

Scriptlet rules are not supported by AdGuard Content Blocker.

Trusted scriptlets​

Trusted scriptlets are scriptlets with extended functionality. It means the same syntax and restrictions. Trusted scriptlet names are prefixed with trusted-, e.g. trusted-set-cookie, to be easily distinguished from common scriptlets.

Note

Trusted scriptlets are not compatible with other ad blockers except AdGuard

Compatibility with different versions of AdGuard

Trusted scriptlets rules are now supported by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.10.141 or later.

Learn more about how to debug scriptlets.

More information about trusted scriptlets can be found on GitHub.

Modifiers for non-basic type of rules​

Each rule can be modified using the modifiers described in the following paragraphs.

Syntax

rule = "[$" modifiers "]" [rule text]
modifiers = modifier0[, modifier1[, ...[, modifierN]]]
  • modifier — set of the modifiers described below.
  • rule text — a rule to be modified.

For example, [$domain=example.com,app=test_app]##selector.

In the modifiers values of the following characters must be escaped: [, ], ,, and \ (unless it is used for the escaping). Use \ to escape them. For example, an escaped bracket looks like this: \].

$app​

$app modifier lets you narrow the rule coverage down to a specific application or a list of applications. The modifier's behavior and syntax perfectly match the corresponding basic rules $app modifier.

Examples

  • [$app=org.example.app]example.com##.textad hides a div with a class textad at example.com and all subdomains in requests sent from the org.example.app Android app.
  • [$app=~org.example.app1|~org.example.app2]example.com##.textad hides a div with a class textad at example.com and all subdomains in requests sent from any app except org.example.app1 and org.example.app2.
  • [$app=com.apple.Safari]example.org#%#//scriptlet('prevent-setInterval', 'check', '!300') applies scriptlet prevent-setInterval only in Safari browser on Mac.
  • [$app=org.example.app]#@#.textad disables all ##.textad rules for all domains while using org.example.app.

Compatibility with different versions of AdGuard

Such rules with $app modifier are supported by AdGuard for Windows, Mac and Android.

$domain​

$domain modifier limits the rule application area to a list of domains and their subdomains. The modifier's behavior and syntax perfectly match the corresponding basic rules $domain modifier.

Examples

  • [$domain=example.com]##.textad — hides a div with a class textad at example.com and all subdomains.
  • [$domain=example.com|example.org]###adblock — hides an element with attribute id equals adblock at example.com, example.org and all subdomains.
  • [$domain=~example.com]##.textad — this rule hides div elements of the class textad for all domains, except example.com and its subdomains.

Please note that there are 2 ways to specify domain restrictions for non-basic rules:

  1. the "classic" way is to specify domains before rule mask and attributes: example.com##.textad;
  2. the modifier approach is to specify domains via $domain modifier: [$domain=example.com]##.textad.

But rules with mixed style domains restriction are considered invalid. So, for example, the rule [$domain=example.org]example.com##.textad will be rejected.

Compatibility with different versions of AdGuard

Such rules with $domain modifier are supported by AdGuard for Windows, Mac, Android, and AdGuard Browser extension for Chrome, Firefox, Edge.

$path​

$path modifier limits the rule application area to specific locations or pages on websites.

Syntax

$path ["=" pattern]

pattern — optional, a path mask to which the rule is restricted. Its syntax and behavior are pretty much the same as with the pattern for basic rules. You can also use special characters, except for ||, which does not make any sense in this case (see examples below).

If pattern is not set for $path, rule will apply only on the main page of website.

$path modifier matches the query string as well.

$path modifier supports regular expressions in the same way basic rules do.

Examples

  • [$path=page.html]##.textad hides a div with a class textad at /page.html or /page.html?<query> or /sub/page.html or /another_page.html
  • [$path=/page.html]##.textad hides a div with a class textad at /page.html or /page.html?<query> or /sub/page.html of any domain but not at /another_page.html
  • [$path=|/page.html]##.textad hides a div with a class textad at /page.html or /page.html?<query> of any domain but not at /sub/page.html
  • [$path=/page.html|]##.textad hides a div with a class textad at /page.html or /sub/page.html of any domain but not at /page.html?<query>
  • [$path=/page*.html]example.com##.textad hides a div with a class textad at /page1.html or /page2.html or any other path matching /page<...>.html of example.com
  • [$path]example.com##.textad hides a div with a class textad at the main page of example.com
  • [$domain=example.com,path=/page.html]##.textad hides a div with a class textad at page.html of example.com and all subdomains but not at another_page.html
  • [$path=/\\/(sub1|sub2)\\/page\\.html/]##.textad hides a div with a class textad at both /sub1/page.html and /sub2/page.html of any domain (please note the escaped special characters)

Compatibility with different versions of AdGuard

Rules with $path modifier are supported by AdGuard for Windows, Mac, Android, and AdGuard Browser extension for Chrome, Firefox, Edge.

url​

$url modifier limits the rule application area to URLs matching the specified mask.

Syntax

url = pattern

where pattern is pretty much the same as pattern of the basic rules assuming that some characters must be escaped. The special characters and regular expressions are supported as well.

Examples

  • [$url=||example.com/ads/*]##.textad hides a div with a class textad at addresses like http://example.com/ads/banner.jpg and even http://subdomain.example.com/ads/otherbanner.jpg.
  • [$url=||example.org^]###adblock hides an element with attribute id equal to adblock at example.org and its subdomains.
  • [$url=/\[a-z\]+\\.example\\.com^/]##.textad hides div elements of the class textad for all domains matching the regular expression [a-z]+\.example\.com^.

Compatibility with different versions of AdGuard

Rules with the $url modifier are supported by AdGuard for Windows, Mac, and Android, running CoreLibs version 1.11 or later.

Information for filters maintainers​

If you maintain a third-party filter that is known to AdGuard, you might be interested in the information presented in this section. Please note that hints will be applied to registered filters only. The filter is considered to be registered and known by AdGuard, if it is present in the known filters index. If you want your filter to be registered, please file an issue to AdguardFilters repo.

Preprocessor directives​

We provide preprocessor directives that can be used by filters maintainers to improve compatibility with different ad blockers and provide:

Note

Any mistake in a preprocessor directive will lead to AdGuard failing the filter update in the same way as if the filter URL was unavailable.

Preprocessor directives can be used in the user rules or in the custom filters.

Including a file​

The !#include directive allows to include contents of a specified file into the filter. It supports only files from the same origin to make sure that the filter maintainer is in control of the specified file. The included file can also contain pre- directives (even other !#include directives). Ad blockers should consider the case of recursive !#include and implement a protection mechanism.

Syntax

!#include file_path

where file_path is a same origin absolute or relative file path to be included.

The files must originate from the same domain but may be located in a different folder.

If included file is not found or unavailable, the whole filter update should fail.

Same-origin limitation should be disabled for local custom filters.

Examples

Filter URL: https://example.org/path/filter.txt

! Valid (same origin):
!#include https://example.org/path/includedfile.txt
!
! Valid (relative path):
!#include /includedfile.txt
!#include ../path2/includedfile.txt
!
! Invalid (another origin):
!#include https://domain.com/path/includedfile.txt

Conditions​

Filters maintainers can use conditions to supply different rules depending on the ad blocker type. When an adblocker encounters an !#if directive, followed eventually by an !#endif directive, it will compile the code inside of the directives block only if the specified condition is true. Condition supports all the basic logical operators.

A conditional directive beginning with an !#if directive must explicitly be terminated with an !#endif directive.

Whitespaces matter. !#if is a valid directive, while !# if is not.

Syntax

!#if (conditions)
rules_list
!#endif

where:

  • !#if (conditions) — start of the block
  • conditions — just like in some popular programming languages, preprocessor conditions are based on constants declared by ad blockers. Ad blocker authors define on their own what exact constants do they declare. Possible values:
    • adguard always declared; shows maintainers that this is one of AdGuard products; should be enough in 95% of cases
    • product-specific constants for cases when you need a rule to work (or not work — then ! should be used before constant) in a specific product only:
      • adguard_app_windows — AdGuard for Windows
      • adguard_app_mac — AdGuard for Mac
      • adguard_app_android — AdGuard for Android
      • adguard_app_ios — AdGuard for iOS
      • adguard_ext_safari — AdGuard for Safari
      • adguard_ext_chromium — AdGuard Browser extension for Chrome (and chromium-based browsers, e.g. new Microsoft Edge)
      • adguard_ext_firefox — AdGuard Browser extension for Firefox
      • adguard_ext_edge — AdGuard Browser extension for Edge Legacy
      • adguard_ext_opera — AdGuard Browser extension for Opera
      • adguard_ext_android_cb — AdGuard Content Blocker for mobile Samsung and Yandex browsers
      • ext_ublock — special case; this one is declared when a uBlock version of a filter is compiled by the FiltersRegistry
  • rules_list — list of rules
  • !#endif — end of the block

Examples

! for all AdGuard products except AdGuard for Safari
!#if (adguard && !adguard_ext_safari)
||example.org^$third-party
domain.com##div.ad
!#endif
! directives even can be combined
!#if (adguard_app_android)
!#include /androidspecific.txt
!#endif

Safari affinity​

Safari is notoriously known for its harsh 150k max limit for filtering rules in content blockers. But in AdGuard for Safari and AdGuard for iOS max rule count is raised to 300k by splitting them into several content blockers. Generally, several filters categories are more or less independent, so there is such content blockers with such categories included:

  • AdGuard General — Ad Blocking, Language-specific
  • AdGuard Privacy — Privacy
  • AdGuard Social — Social Widgets, Annoyances
  • AdGuard Security — Security
  • AdGuard Other — Other
  • AdGuard Custom — Custom

User rules and Allowlist are added to every content blocker.

The main issue with using multiple content blockers is that rules inside these content blockers cannot influence each other. This may lead to different unexpected issues. So filters maintainers may use !#safari_cb_affinity to define Safari content blockers affinity for the rules inside of the directive block.

Syntax

!#safari_cb_affinity(content_blockers)
rules_list
!#safari_cb_affinity

where:

  • !#safari_cb_affinity(content_blockers) — start of the block
  • content_blockers — comma-separated list of content blockers. Possible values:
    • general — AdGuard General content blocker
    • privacy — AdGuard Privacy content blocker
    • social — AdGuard Social content blocker
    • security — AdGuard Security content blocker
    • other — AdGuard Other content blocker
    • custom — AdGuard Custom content blocker
    • all — special keyword that means that the rules must be included into all content blockers
  • rules_list — list of rules
  • !#safari_cb_affinity — end of the block

Examples

! to unhide specific element which is hidden by AdGuard Base filter:
!#safari_cb_affinity(general)
example.org#@#.adBanner
!#safari_cb_affinity
! to allowlist basic rule from AdGuard Tracking Protection filter filter:
!#safari_cb_affinity(privacy)
@@||example.org^
!#safari_cb_affinity

Hints​

"Hint" is a special comment, instruction to the filters compiler used on the server side (see FiltersRegistry).

Syntax

!+ HINT_NAME1(PARAMS) HINT_NAME2(PARAMS)

Multiple hints can be applied.

NOT_OPTIMIZED hint​

For each filter, AdGuard compiles two versions: full and optimized. Optimized version is much more lightweight and does not contain rules which are not used at all or used rarely.

Rules usage frequency comes from the collected filter rules statistics. But filters optimization is based on more than that — some filters have specific configuration. This is how it looks like for Base filter:

"filter": AdGuard Base filter,
"percent": 30,
"minPercent": 20,
"maxPercent": 40,
"strict": true

where:

  • filter — filter identifier
  • percent — expected optimization percent ~= (rules count in optimized filter) / (rules count in original filter) * 100
  • minPercent — lower bound of percent value
  • maxPercent — upper bound of percent value
  • strict — if percent < minPercent OR percent > maxPercent and strict mode is on then filter compilation should fail, otherwise original rules must be used

In other words, percent is the "compression level". For instance, for the Base filter it is configured to 40%. It means that optimization algorithm should strip 60% of rules.

Eventually, here are the two versions of the Base filter for AdGuard Browser extension:

If you want to add a rule which should not be removed at optimization use the NOT_OPTIMIZED hint:

!+ NOT_OPTIMIZED
||example.org^

And this rule will not be optimized only for AdGuard for Android:

!+ NOT_OPTIMIZED PLATFORM(android)
||example.org^

PLATFORM and NOT_PLATFORM hints​

Used to specify the platforms to apply the rules. List of existing platforms and links to Base filter, for example, for each of them:

Examples

This rule will be available only in AdGuard for Windows, Mac, Android:

!+ PLATFORM(windows,mac,android)
||example.org^

This rule will be available for every platform except AdGuard for Safari, AdGuard Content Blocker, and AdGuard for iOS:

!+ NOT_PLATFORM(ext_safari, ext_android_cb, ios)
||example.org^

How to debug filtering rules​

It may be possible to create simple filtering rules "in your head" but for anything even slightly more complicated you will need additional tools to debug and iterate them. There are tools to assist you with that. You can use DevTools in Chrome and its analogs in other browsers but most AdGuard products provide another one — Filtering log.

Filtering log​

Filtering log is an advanced tool that will be helpful mostly to filter developers. It lists all web requests that pass through AdGuard, gives you exhaustive information on each of them, offers multiple sorting options, and has other useful features.

Depending on which AdGuard product you are using, Filtering log can be located in different places.

  • In AdGuard for Windows you will find it inside Ad Blocker tab or via the tray menu;
  • In AdGuard for Mac it is under Settings → Advanced → Filtering log;
  • In AdGuard for Android it is a separate item in the side menu, also filtering log for a specific app or website is accessible from the Assistant.
  • In AdGuard Browser extension it is accessible from the Miscellaneous settings tab or by right-clicking the extension icon. Only Chromium- and Firefox-based browsers show applied element hiding rules (including CSS, ExtCSS) and JS rules and scriptlets in their Filtering logs.

In AdGuard for iOS and in AdGuard for Safari Filtering log does not exist because of the way content blockers are implemented in Safari. AdGuard does not see the web requests and therefore cannot display them.

Selectors debugging mode​

Sometimes, you might need to check the performance of a given selector or a stylesheet. In order to do it without interacting with JavaScript directly, you can use a special debug style property. When ExtendedCss meets this property, it enables the debugging mode either for a single selector or for all selectors, depending on the debug value.

Open the browser console while on a web page to see the timing statistics for selector(s) that were applied there. Debugging mode displays the following stats as object where each of the debugged selectors are keys, and value is an object with such properties:

Always printed:

  • selectorParsed — text of eventually parsed selector
  • timings — list of DOM nodes matched by the selector
    • appliesCount — total number of times that the selector has been applied on the page
    • appliesTimings — time that it took to apply the selector on the page, for each of the instances that it has been applied (in milliseconds)
    • meanTiming — mean time that it took to apply the selector on the page
    • standardDeviation — standard deviation
    • timingsSum — total time it took to apply the selector on the page across all instances

Printed only for remove pseudos:

  • removed — flag to signal if elements we removed

Printed if elements are not removed:

  • matchedElements — list of DOM nodes matched by the selector
  • styleApplied — parsed rule style declaration related to the selector

Examples

Debugging a single selector:

When the value of the debug property is true, only information about this selector will be shown in the browser console.

#$?#.banner { display: none; debug: true; }

Enabling global debug:

When the value of the debug property is global, the console will display information about all extended CSS selectors that have matches on the current page, for all the rules from any of the enabled filters.

#$?#.banner { display: none; debug: global; }

Testing extended selectors without AdGuard

ExtendedCss can be executed on any page without using any AdGuard product. In order to do that you should copy and execute the following code in a browser console:

!function(e,t,d){C=e.createElement(t),C.src=d,C.onload=function(){alert("ExtendedCss loaded successfully")},s=e.getElementsByTagName(t)[0],s?s.parentNode.insertBefore(C,s):(h=e.getElementsByTagName("head")[0],h.appendChild(C))}(document,"script","https://AdguardTeam.github.io/ExtendedCss/extended-css.min.js");

Alternatively, install the ExtendedCssDebugger userscript.

Now you can now use the ExtendedCss from global scope, and run its method query() as Document.querySelectorAll().

Examples

const selector = 'div.block:has=(.header:matches-css(after, content: Ads))';

// array of HTMLElements matched the `selector` is to be returned
ExtendedCss.query(selector);

Debugging scriptlets​

If you are using AdGuard Browser extension and want to debug a scriptlet or a trusted scriptlet rule, you can get additional information by opening the Filtering log. In that case, scriptlets will switch to debug mode and there will be more information in the browser console.

The following scriptlets are especially developed for debug purposes:

The following scriptlets also may be used for debug purposes:

Good luck with creating filters!​

We wish you luck with creating you own ad filters.

If you need an advice on how to create your own filters properly, our forum has a special section dedicated to writing your own filtering rules.