Filter List Format Compatibility

Filter Format Compatibility

This project mainly aims to provide a highly optimized method of applying EasyList-style rules to network requests, to perform URL filtering. The project also supports other filter rule formats that have been developed and promoted by other blocking tools.

This document describes which filter rule formats that are supported by this project, and to what degree. Support is broken down into three tiers:

• full support: The rule parser understands the rule, and the matching engine understands how to apply it to a network request.
• parsed but ignored: The parser understands the rule, but the rule is ignored by the matching engine.
• not supported: The parser does not understand the rule, and does not maintain any internal understanding of the rule.

AdBlock Plus

AdBlock Plus has filters for blocking network requests, hiding page elements, and rules for overwriting / excepting either of the above.

Full Support

We support most of the rule formats defined by AdBlock Plus. Unless specifically mentioned below, the rules are fully supported (both in "main" and "exception" form).

Parsed but Ignored

• All element rules, indicating that HTML elements should be hidden or collapsed.
• The ping option, which indiciates a request from a <a ping> element, or a navigator.sendBeacon() call.
• The popup option, which indicates that new pages should not be opened in new tabs or windows from a given url.
• The csp option, which indicates a given content security policy should be applied to the page.
• The elemhide option, which, when used in exception rules, indiciates that element hiding rules should not be applied to matching domains.
• The generichide option, which indicates that generic (i.e. non-domain specific) element hiding rules should not be applied to matching URLs and filters.
• The genericblock option, which indicates that generic (i.e. non-domain specific) network rules should not be applied to matching URLs.

If a filter rule has one of the above options applied to it, but also some other supported options (e.g. the rule example.org$script,popup), this library will apply the fully supported option, script, but ignore the non-supported one, popup.

Not Supported

• Regular expression based rules of any kind
• The websocket rule

AdGuard

AdGuard supports a super set of AdBlockPlus's rule formats. This section only describes support for rule formats supported by AdGuard, but not AdBlockPlus. We do not support AdGuard filter rule formats not mentioned below.

Parsed but Ignored

• The empty rule, which indicates that matching requests should be sent an empty 200 request, instead of no request.

uBlock

uBlock supports a super set of AdBlockPlus's rule formats. This section only describes support for rule formats supported by uBlock, but not AdBlockPlus. We do not support uBlock filter rule formats not mentioned below.

Not Supported

• The important rule, which provides a way to mark a rule as ignored by exception rule.
• The redirect rule, which indicates that matching requests should be replaced with new requests.