Almost a month after releasing version 144, Mozilla has launched Firefox 145, the latest update to its popular open-source web browser, now available for download.

The most visible addition in the new version is the ability to add, edit, and delete comments directly in PDFs. Users can now jot down notes, questions, or reminders right inside a document, with a convenient comment sidebar to manage annotations.

Another quality-of-life improvement is the new tab group preview feature. By hovering over a tab group name, users can instantly see which pages are inside without expanding the group.

Moreover, Firefox 145 expands its sharing tools with Copy Link to Highlight, which allows users to share a specific section of a webpage. When the recipient opens the link, Firefox automatically highlights the selected text.

Another major innovation arriving in this release is Semantic History Search. This experimental feature enables users to find previously visited pages using natural-language or concept-based queries — for example, searching for “that Linux article about Varnish” — all processed locally to protect user privacy.

On the visual side, Firefox 145 updates the browser’s UI consistency. Horizontal tabs now feature slightly rounded corners to match the style of vertical tabs, while buttons and text inputs — including the address bar — have been refined for a more cohesive appearance. Additionally, when no extensions are installed, clicking the Extensions button now offers suggestions and links to the Firefox Add-ons store, encouraging users to explore customization options.

Developers and web enthusiasts will also find new platform enhancements. Firefox 145 adds support for the Atomics.waitAsync proposal, enabling non-blocking synchronization between threads for shared memory operations. It also introduces initial support for the Integrity-Policy header, which enforces subresource integrity for scripts and strengthens web security.

For multimedia support, Firefox 145 now includes Matroska (.mkv) compatibility for widely used codecs, such as AVC, HEVC, VP8, VP9, AV1, AAC, Opus, and Vorbis, ensuring smoother playback of open video formats. The release also supports the text-autospace CSS property, allowing better spacing between characters across mixed writing systems.

However, the release marks the end of an era: Firefox 145 officially drops support for 32-bit Linux systems. Mozilla now recommends that all Linux users move to 64-bit builds for continued updates and security fixes.

Those eager to immediately download this update can do so directly from Mozilla’s server.

Windows and macOS users can expect an over-the-air update within the following days. Users of rolling-release Linux distributions can expect Firefox 145 to appear in their repositories within the next few days.