Firefox iOS Ad Blocker: Built-In, EasyList, Off by Default

Mozilla shipped a built-in ad blocker for Firefox on iOS yesterday. No extension, no install — it's a toggle in the browser settings, powered by Apple's WebKit Content Blocker API and the EasyList filter list. On the same week Google finished purging uBlock Origin from the Chrome Web Store, that timing is not a coincidence.

What is the Firefox iOS ad blocker and how does it work?

The Ad Blocker for Firefox on iOS blocks third-party ads and ad-related trackers before they load. Mozilla built it on Apple's WebKit Content Blocker technology with the community-maintained EasyList filter list — the same ruleset that powers most desktop blockers. It's off by default; you enable it at Settings > Browsing > Ad Blocker. It layers on top of Firefox's existing Enhanced Tracking Protection.

The limits are honest ones: first-party ads served directly by the site, search-result ads, and sponsored shortcuts in Firefox's new-tab page still appear. This is a baseline, not a uBlock replacement.

Why does built-in ad blocking on iOS matter now?

Because mobile browsers can't do extension-based ad blocking the way desktop can — and two days after Google removed uBlock Origin from the Chrome Web Store, the browser vendors are drawing different lines. Mozilla's answer on iOS: make the blocker part of the browser itself. Brave hosts MV2 holdouts on its own backend. Chrome ships prefixed webRequest restrictions. The blocker used to be a bolt-on; now it's becoming a core browser feature, with the vendor deciding the ruleset.

The signal to watch: EasyList — a community list no single company controls — is now baked into Apple's API and shipped inside Mozilla's browser. Ad blocking is consolidating from a user-installed arms race into a platform-level feature. That's more stable for users, and more leverage for the browser vendors.