Mozilla speeds Firefox release schedule to biweekly
Mozilla plans to speed up Firefox's release cadence from every four weeks to every two weeks, starting in September 2026, in an experimental change announced by director of engineering Sylvestre Ledru. The Extended Support Release (ESR) schedule, which offers longer-term stability for enterprises and cautious users, will remain unaffected and continue on its annual cycle, with the next ESR version due imminently. Mozilla says the faster pace does not mean features will be rushed out before they are ready, and it will monitor the change closely before deciding whether to keep it.
Under the new schedule, Firefox 155 will arrive on 1 September 2026 rather than 15 September, with releases roughly a fortnight apart thereafter; Firefox 153 and 154 will still follow the current four-week rhythm. Mozilla previously used a similar cadence over a decade ago, and Google made a comparable move for Chrome in March. In the nearer term, Firefox 153, due for release on 21 July, will become the next ESR version with security support until at least late 2027, and brings features including PDF merging and image insertion, QR code generation for offline page sharing, support for the EU's new Qualified Website Authentication Certificates, a location-use indicator icon, and a change that removes extensions' local-file access by default.
In short
- Firefox moves to fortnightly releases from September 2026, on trial.
- ESR releases stay annual; unaffected by the faster cadence.
- Firefox 153, out 21 July, becomes the next ESR with PDF and security upgrades.
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The strongest fair case each way — we don't pick a winner.
The case for
Accelerating release cycles improves security and user experience by delivering patches and features more frequently, allowing Mozilla to respond quickly to vulnerabilities and user demands whilst aligning with industry practice—Chrome made the same move, and modern development favours small, frequent updates over large, infrequent ones. The Extended Support Release option remains available for those prioritising stability, giving users choice.
The case against
More frequent releases create unnecessary upgrade burden for all users, risk compressing testing time and introducing instability, and force enterprises and those with limited connectivity to manage constant version changes. Whilst the ESR option exists, regular users lose a stable release track, fragmenting the user base and multiplying compatibility challenges for extensions and third-party integrations. The trade-off between novelty and predictability should favour those seeking reliability over rapid iteration.
Explained simply
Firefox is one of the world's most widely used web browsers, an alternative to Google Chrome and Microsoft Edge that millions of people use to access the internet. Software developers regularly release new versions of browsers to add features, fix security problems and improve performance; the speed at which these versions arrive affects how quickly users can access improvements and security patches.
Mozilla, the company behind Firefox, has decided to accelerate its release schedule, moving from new versions roughly every four weeks to every two weeks. The firm emphasises that the faster pace does not mean features will be released before they are fully tested, and it plans to assess how the change works before deciding whether to keep it permanent. Google made a similar change to its Chrome browser several years ago.
The change does not affect Firefox's Extended Support Release version, which is designed for people who prioritise stability over speed and is commonly used by large organisations. Enterprise users and cautious individuals will continue to receive updates on an annual basis, meaning they can opt for predictability rather than constantly updating their software.