Open Ad Blocker

Fully declarative ad and tracker blocker. No telemetry, no acceptable ads, no servers.

Open Ad Blocker is a content blocker built on Chrome's Declarative Net Request API. The rules are compiled from public filter lists at build time and evaluated by the browser, so filtering starts before any page script and keeps working even when the extension's service worker is suspended. What you get • Network blocking for ads and trackers from EasyList, EasyPrivacy and Peter Lowe's list. • Cosmetic filtering: ad placeholders are hidden before they are painted, including per-site rules. • Four modes per site: Off, Basic, Optimal and Complete. Changing a mode needs no reload. • An element picker: point at something, get a robust selector, hide it. • Your own filter rules in Adblock Plus syntax, converted locally, with a clear explanation for every line that cannot be converted. • An allowlist with import and export. • A filter log that names the original filter line behind a match. What it does not do • No telemetry, no account, no server, no analytics. • No "acceptable ads", no paid exceptions, no partner allowlist. • No remote code, no eval, no host permissions. Honest about limits Some things are impossible in Manifest V3 without host permissions: $removeparam, $removeheader, $csp and redirect rules are dropped, and the filter log cannot show the blocked URL in a store build. Every limitation is written down in docs/limitations.md in the repository. Effectiveness On a fixed 113-page corpus we measured this extension against no blocker and against uBO Lite. On classified ad/tracker requests the result was parity with uBO Lite (median difference 0, 95% CI 0–0), and there was no load-time regression against no blocker. We do not claim to be better, faster or more effective. The full method and numbers are public in docs/MEASUREMENTS.md. Licence GPL-3.0-or-later. Readable source, no obfuscation, no tracking.