What does the double pipe (||) signify in an adblock filter rule?

The double pipe || marks a hostname boundary anchor. For example, ||example.com/banner.js matches http://example.com/banner.js, https://sub.example.com/banner.js, and https://example.com:8080/banner.js, but will NOT match https://another-example.com/banner.js.

What does the caret (^) symbol mean in network filters?

The caret ^ represents a separator character. It matches anything that is not a letter, digit, underscore, hyphen, or percentage sign (such as /, ?, :, &, or the end of the URL string).

How do cosmetic filters (##) differ from network filters?

Network filters prevent HTTP/HTTPS requests from being sent by the browser. Cosmetic filters (##) do not block network traffic; instead, they inject CSS rules into the webpage DOM (such as display: none !important) to hide visual page elements.

What is the difference between $third-party and $~third-party?

The $third-party option restricts a rule so it only triggers when a resource is requested from a domain different from the page origin. Adding a tilde ($~third-party) inverts the rule, making it apply only to first-party requests.

How do exception whitelist rules (@@) work?

An exception rule starts with @@. When a URL matches an exception rule, it overrides matching blocking rules, permitting the request or disabling cosmetic filtering on that specific domain.

SEO & Marketing

uBlock Origin & AdBlock Filter Rule Syntax & Regex Tester

Name: uBlock Origin & AdBlock Cosmetic & Network Filter Syntax Tester
Author: AnshuTechy

Test network request filters, CSS cosmetic element hiding selectors (`##`), procedural scriptlets (`##+js`), and exception rules (`@@`) against standard Adblock Plus and uBlock Origin filter syntax specifications.Documentation & FAQs ↓

uBlock Origin & AdBlock Cosmetic & Network Filter Syntax Tester — Interactive Console

Runs locally in your browser • Instant output

Rule Presets:

Filter Rule (uBlock Origin / Adblock Plus Syntax)

Supports network anchors (||, |), separators (^), cosmetic selectors (##), and scriptlets (##+js).

Test URL (Simulate Request Matching)

Tests against internal declarativeNetRequest / regex simulator.

Rule Type Classification

Network Request Block

Engine Target: Network WebRequest / DNR

Syntax Validation

Valid Adblock Rule

Compatible with uBlock Origin, ABP, and AdGuard

Active Options & Flags

$third-party$script

Internal Regex Equivalent Engine Representation

^https?://([a-z0-9-]+\.)*doubleclick\.net([/:?&=#]|$)

Underlying compiled pattern evaluated by browser extension engines when matching URLs.

Rule Triggers · Action Applied

URL matches filter pattern "^https?://([a-z0-9-]+\.)*doubleclick\.net([/:?&=#]|$)". Network request will be BLOCKED at declarative/webRequest hook.

Step-by-Step Instructions

4 Steps to Completion

1Phase 1

Paste an adblock filter rule (e.g., ||example.com/ads/*$image,script,third-party or example.com##.ad-banner) into the input.

2Phase 2

Inspect the parsed rule category: Network Filter, Cosmetic Filter, Scriptlet, or Whitelist Exception.

3Phase 3

Review token breakdown, matched domains, activated modifier flags, and regex translation.

4Phase 4

Test candidate URLs or DOM snippets against the rule to confirm blocking behavior.

Practical Use Cases & Real-World Scenarios

Authoring Custom uBlock Origin Filters

Ensure newly written anti-ad or anti-tracker filter rules do not break page layouts with syntax errors before adding to 'My Filters'.

Hiding Intrusive Web Page Elements

Draft precise cosmetic hiding rules (domain.com##.floating-newsletter-modal) that target sticky banners without affecting content.

Maintaining Community Adblock Lists

Lint and debug hundreds of rules to ensure standard compatibility across uBlock Origin, AdGuard, and Brave Shields.

Related Editorial Guide on AnshuTechy10 Best Ad Blockers Extensions for Chrome in 2026

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100% free, private in-browser utility with zero server uploads.

uBlock Origin & AdBlock Filter Rule Syntax & Regex Tester

Step-by-Step Instructions

Practical Use Cases & Real-World Scenarios

Network Rule Parser

Cosmetic Element Hiding (##)

Filter Modifier Inspector

Exception Rule (@@) Debugger

Frequently Asked Questions

10 Best Ad Blockers Extensions for Chrome in 2026

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