A browser extension that blocks ads in Chrome under Manifest V3 using network-layer interception outside the browser's declarativeNetRequest limits

Google's Manifest V3 transition disabled uBlock Origin for around 40 million Chrome users by imposing hard rule limits on the declarativeNetRequest API that make full dynamic filtering impossible. The stranded users cannot get full ad blocking inside Chrome today. The opportunity is a browser extension that moves the filtering logic to a local proxy or native companion app running outside the browser sandbox, so Chrome rule limits are irrelevant -- the extension itself just routes traffic through a localhost interceptor that does the heavy filtering.

Demand Breakdown

2,053

Social Proof 5 sources

Chrome MV3 declarativeNetRequest hard rule limits disable uBlock Origin for 40M users

2024-10-01

1,024 HN

Developer demand for zero-config cross-browser extension build tooling is confirmed at scale

2024-05-01

406 HN

Google confirmed uBlock Origin removal from Chrome, accelerating user flight to Firefox and Brave

2023-11-01

277 HN

Google pulls the plug on uBlock Origin -- mass community anger and no viable Chrome replacement

2024-08-01

227 HN

uBlock Origin Has Been Disabled -- Chrome users actively searching for alternatives

2025-02-01

119

Gap Assessment

CompetitiveMultiple tools exist but differentiation opportunities remain

5 tools exist (uBlock Origin Lite (MV3), Firefox + uBlock Origin, AdGuard Desktop, Plasmo, Extension.js) but gaps remain: Confirmed downgrade with no dynamic filtering, missing cosmetic filters and many tracker categories. The creator explicitly calls it a lite version with reduced capability.; Requires switching browsers. Chrome users with enterprise configs, extension ecosystems, or sync tied to Google accounts cannot easily migrate. The 40M user gap is Chrome-specific..

Features2 agent-ready prompts

Local proxy interceptor that filters HTTP/HTTPS traffic before it reaches Chrome, with a lightweight MV3 extension shell that routes the browser through localhost

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Zero-config cross-browser extension build CLI that compiles a single MV3-compliant source tree to Chrome, Firefox, and Safari with one command

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Competitive LandscapeFREE

Product	Does	Missing
uBlock Origin Lite (MV3)	Official MV3 port of uBlock Origin by gorhill. Static rule lists only, ships as an MV3-compliant extension.	Confirmed downgrade with no dynamic filtering, missing cosmetic filters and many tracker categories. The creator explicitly calls it a lite version with reduced capability.
Firefox + uBlock Origin	Firefox still supports MV2 and full uBlock Origin. Brave runs its own internal ad engine bypassing MV3 entirely.	Requires switching browsers. Chrome users with enterprise configs, extension ecosystems, or sync tied to Google accounts cannot easily migrate. The 40M user gap is Chrome-specific.
AdGuard Desktop	AdGuard offers a system-level network filter (desktop app) and an MV3 browser extension that uses their own filter engine.	AdGuard MV3 extension is still limited by the same declarativeNetRequest caps for custom rules. The desktop app requires a separate installation and costs $2.99/mo subscription.
Plasmo	Paid, opinionated cross-browser extension framework for developers with a hosted CI/CD layer.	Paid tier, framework lock-in, and opinionated structure. Extension.js (open-source, zero-config) hit 381 HN points showing developer appetite for an alternative.
Extension.js	Open-source zero-config CLI for cross-browser extension builds.	Open-source with no monetization model, early ecosystem, no hosted tooling or team features. A paid SaaS layer on top (CI/CD, cross-browser testing, distribution) is the white space.