Brijesh Desai 
Firefox adds built-in ad blocker to iOS, using Apple’s WebKit Content Blocker and EasyList to block many third-party ads and trackers without extra extensions.
Firefox adds built-in ad blocker to iOS
Firefox adds built-in ad blocker to iOS, giving iPhone and iPad users a native way to block many third-party ads and ad-related trackers without installing separate extensions. The feature, called Ad Blocker, is optional and turned off by default, but can be enabled in the browser’s settings.
The update arrives with Firefox 155 for iOS after a few weeks of testing. Mozilla says the feature is designed to reduce clutter, overlays, pop-ups, and some forms of tracking before pages fully load.
How the ad blocker works
Firefox’s new ad blocker relies on two main components:
- Apple’s WebKit Content Blocker API – the same technology used by Safari ad-blocking extensions.
- The EasyList filter list – a widely used, community-maintained list of known ad and tracker domains.
When enabled, Firefox uses these rules to block requests to known ad servers and tracking domains before they load. This can reduce page clutter, improve loading times, and lower data usage on mobile networks.
Because Firefox on iOS must use Apple’s WebKit engine, the ad blocker works within Apple’s constraints rather than as a fully independent engine. That is why Mozilla integrated the feature directly into the app instead of offering it as a separate extension.
What the ad blocker blocks
According to Mozilla, the built-in ad blocker targets:
- Third-party advertising networks and exchanges.
- Many third-party ads served on websites.
- Ad-related trackers.
- Pop-ups and overlay ads.
It complements Firefox’s existing Enhanced Tracking Protection, which already blocks many web trackers on iOS. The new Ad Blocker focuses more specifically on ads and ad infrastructure rather than general tracking.
What it does not block
Mozilla is clear that the feature will not remove every ad. The ad blocker will not block:
- Ads served directly by the website you are visiting.
- Ads shown in search results (for example, on Google or Bing).
- Sponsored shortcuts and other sponsored content on Firefox’s home or new tab page.
Mozilla also notes that the blocker only works inside Firefox. It will not affect ads in other apps or in Safari.
How to enable the ad blocker
The feature is off by default and is being rolled out gradually. Some users may not see it immediately. To enable it when available:
- Open the Firefox app on iPhone or iPad.
- Tap the menu (three dots).
- Go to Settings → Browsing.
- Toggle on Ad Blocker.
You can also turn Ad Blocker on or off for individual sites from the site menu while browsing. Mozilla says the feature requires Remote Improvements to be enabled so fixes and updates can be pushed between full app releases.
Why this matters for iOS users
Before this update, iOS users who wanted ad blocking in Firefox had to rely on Safari content-blocker extensions or third-party browsers with built-in blockers. Firefox’s new native ad blocker simplifies the experience by integrating the functionality directly into the app.
The move also reflects growing demand for privacy-focused browsing on mobile devices. By combining EasyList with WebKit’s content-blocking API, Mozilla can offer a more consistent experience across its desktop, Android, and iOS products, even though the iOS version still operates within Apple’s engine restrictions.
Summary: Firefox adds built-in ad blocker to iOS, using WebKit Content Blocker and EasyList to block many third-party ads and trackers. The feature is optional, off by default, and does not block site-owned ads, search-result ads, or Firefox’s own sponsored content.