Mozilla will test two-week Firefox releases starting in 2026
Firefox Desktop and Android are slated to move from four-week to two-week releases in September 2026, while ESR stays on its annual schedule.
By Renata Fuchs · Policy Reporter
· 3 min read
Mozilla plans to shift Firefox Desktop and Firefox for Android from a four-week release cycle to a two-week cycle starting in September 2026, according to engineering director Sylvestre Ledru. The change is framed as an experiment, not a permanent reset, and it does not apply to Firefox Extended Support Release, which remains annual.
Ledru told Mozilla’s dev-platform mailing list that the faster schedule should not force unfinished work into production. Features can still miss a train if they are not ready, he said, and Mozilla will watch the process and change course if needed. Mozilla has not specified what metrics will determine whether the experiment continues.
The practical effect is already reflected in Mozilla’s public release calendar. Firefox 153 and 154 remain on the existing four-week cadence, while Firefox 155 is now targeted for September 1, 2026, rather than September 15. After that, the calendar shows releases landing at roughly two-week intervals.
The move brings Mozilla closer to a release model that Chrome has also been tightening. Google announced a similar Chrome cadence change in March, following earlier shifts to six-week releases in 2010 and four-week releases in 2021. For browser vendors, the operational bet is that smaller, more frequent releases reduce the backlog and get security and platform changes to users faster. The tradeoff is more pressure on testing, add-on compatibility and enterprise IT teams that prefer fewer changes to certify.
Firefox 153 becomes the next ESR base
Before the 2026 cadence test begins, Mozilla is preparing Firefox 153, which its calendar lists for Tuesday, July 21. The stable release notes are not yet filled in, but Mozilla’s beta notes describe several user-facing changes, many of them in the browser’s built-in PDF tooling.
Firefox 153 is expected to let users combine multiple PDFs by dragging them into the PDF sidebar. It will also allow images to be inserted into PDFs as new pages and will improve text highlighting inside PDFs. Mozilla is also adding QR code generation for sharing web pages in offline contexts such as print.
On the identity and security side, Firefox 153 can verify and show Qualified Website Authentication Certificates, or QWACs, used under the European Union’s eIDAS rules. Extensions will also lose local-file access by default, though users can grant that permission separately. If a tab is using location data, Firefox will show a map-pin indicator in the address bar.
Other planned additions include typed address-bar commands for page color picking and access to experimental Labs features. Firefox 153 also brings experimental JPEG XL support, improved pop-up video controls and HDR video playback on Windows systems with compatible GPUs and drivers. On macOS, Mozilla is adding support for Fn+F to enter full-screen mode.
Firefox 153 is also significant because it is the next ESR version. Mozilla’s ESR builds receive security updates for at least 15 months, putting Firefox 153 support into late 2027. Firefox 115, an older ESR line, is still receiving updates and is scheduled to keep doing so until March 2027.
The ESR base also affects downstream browsers. Firefox 153 underpins the latest beta of Waterfox, the Firefox fork that has positioned itself as AI-free and recently added built-in ad blocking.
This story draws on original reporting from The Register.
