Firefox 148 brings central AI control and new web standards

Mozilla has released Firefox 148. The new version's most important innovation is a central management page for all of the browser's AI functions. The "Block AI improvements" toggle is enabled by default and prevents pop-ups and prompts for AI functions.

The new "AI Control" section in the settings allows granular control of individual features. Users can choose between three states for each function: "Available" makes features visible and usable, "Enabled" activates them via opt-in, while "Blocked" completely hides them and deletes locally stored data for on-device models. Controllable functions include translations, automatic image descriptions in PDFs, link previews, and chatbots from Anthropic Claude, ChatGPT, Microsoft Copilot, Google Gemini, and Le Chat Mistral. The settings are preserved across updates.

Mozilla has also decoupled remote browser changes from telemetry. Users now receive configuration updates without having to share usage data or participate in experimental studies. The Windows 10 version now also supports Firefox Backup for users who have enabled "Clear history when Firefox is closed" in the settings – the backups do not include data intended for deletion.

For translation functions, Firefox 148 now supports Chinese (Traditional) in both directions, as well as Vietnamese. Screen reader improvements affect the display of mathematical formulas in PDF documents. A fix addresses the issue where language packs were deactivated after a major update. On Windows, drag-and-drop of downloaded images into Adobe Illustrator also works correctly – the image is inserted, not its URL.

WebGPU in Service Workers and New Security APIs

For web developers, Firefox 148 brings support for WebGPU in Service Workers. The GPU-accelerated graphics interface is thus available in all worker contexts and enables computationally intensive operations in the background – for example, for browser extensions or for tabs that need to share resources over different periods.

With the Trusted Types API, Mozilla is integrating an important security mechanism against Cross-Site Scripting attacks. The API enforces that inputs undergo a transformation before they reach critical DOM sinks such as innerHTML. Developers activate the protection via a Content Security Policy header. Additionally, the Sanitizer API is available, which enables secure HTML manipulation with methods such as element.setHTML() and document.parseHTML(). The configurable functions can replace third-party libraries like DOMPurify.

For JavaScript developers, the new version brings support for Iterator.zip() and Iterator.zipKeyed() from the Joint Iteration Proposal. The methods allow combining multiple iterators into grouped values – similar to the functions of the same name in other programming languages.

CSS Extensions for Anchor Positioning and Shapes

In the CSS area, Mozilla is introducing the position-try-order property, which controls the order of fallback positioning attempts in CSS Anchor Positioning when elements would extend beyond the viewport. The new shape() function allows defining responsive freeform shapes, for example, for clip-path. Unlike the path() function, shape() supports CSS units and mathematical functions, which simplifies handling.

Further innovations for developers include location.ancestorOrigins and NavigationPrecommitController.addHandler() from the Navigation API. The initial about:blank document is now executed in a web-compatible manner – synchronously and without a second parser document.

The introduction of central AI control is a response to controversies surrounding Mozilla's AI strategy. In December 2025, CEO Anthony Enzor-DeMeo presented his vision of a "modern AI browser," which, not least among privacy-conscious users, triggered fears of data leakage to third-party AI services.

Details on all changes can be found in the official Release Notes.

(fo)