Firefox moves to biweekly releases from September 2026

Mozilla plans to double Firefox’s release pace for desktop and Android, moving from a four-week cadence to two weeks starting in September 2026. The change was announced on the dev-platform@mozilla.org mailing list by Sylvestre Ledru, Mozilla’s director of engineering.

“We are planning to move Firefox Desktop and Android from a 4-week release cadence to a 2-week release cadence starting in September 2026. ”This will be an experiment… This does not mean that all work needs to ship twice as fast. Work that is not ready should not be rushed, and features can still take the time they need to bake. “The current target is to release Firefox 155 on September 1, 2026, instead of September 15 … ”We will closely monitor how this change works in practice and adjust if needed."

The updated Firefox release calendar already reflects the shift. Firefox 153 and 154 stay on the current four-week schedule, while Firefox 155 moves up to September 1, 2026. After that, releases are listed at roughly two-week intervals.

Mozilla has done this before, though not recently. The Register notes that the company last made a similar change more than a decade ago. It also follows Google’s move on Chrome, after earlier shifts to six-weekly releases in 2010 and four-weekly releases in 2021.

Firefox 153 features and ESR support

Before the cadence changes, Firefox 153 is due on Tuesday, July 21 and will become the next Extended Support Release (ESR). That means it will receive security updates for at least 15 months, taking support to late 2027. The Register also notes that Firefox 115 is still being updated and is now set to continue until March 2027.

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Based on the beta release notes, Firefox 153 includes:

• more PDF editing tools, including merging multiple PDFs by drag-and-drop in the sidebar
• the ability to insert images into PDFs as new pages
• improved text highlighting in PDFs
• QR code generation for sharing web pages offline
• support for displaying the EU’s Qualified Website Authentication Certificates (QWACs) under eIDAS
• a new map-pin icon when a tab is using your location
• additional address bar commands, including color picking and access to experimental Labs features
• experimental JPEG XL support
• improved picture-in-picture controls
• HDR video playback on Windows with a compatible GPU and drivers
• support on macOS for the Fn+F shortcut to enter full-screen mode

There is also a security change: extensions will lose local-file access by default, though users can grant that permission separately.

Firefox 153 is also the base for the latest beta of Waterfox, which The Register describes as an AI-free fork that recently added built-in ad blocking.