For the first time in browser history, Firefox, Chrome, and Edge are all shipping on the same two-week cadence. Firefox 156 landed on September 11, 2026 — just ten days after Firefox 155 on September 1 — completing the transition Mozilla announced in July. Chrome 153 had already shifted to the same beat on September 8, and Edge 152 began its biweekly schedule on August 27.
What Changed and Why
Mozilla's four-week release cycle dated back to 2012, when the browser moved from major versioned releases to rapid iteration. The shift to two weeks mirrors a change Chrome made internally to speed up security patches reaching users. The core argument: a critical vulnerability patched on day one of a four-week cycle could sit unshipped for up to 28 days for users who don't manually update. At two weeks, that window is halved.
The change also compresses the time between a web platform feature landing in a browser's source tree and shipping to production users. Beta periods remain — Firefox runs a two-week beta before each release — so developers still have a preview window, just a tighter one.
What This Means for Developers and Designers
The practical implications are significant. CSS and JavaScript features that clear the standards process can now reach stable Firefox roughly twice as fast as before. Features like @starting-style, popover enhancements, and newer color() function improvements are already queued in the Firefox Nightly pipeline and will hit stable users sooner.
On the testing side, the new cadence means cross-browser inconsistencies close faster. When all three engines ship on aligned two-week cycles, the window where a feature is "supported in Chrome but not yet in Firefox" shrinks from months to weeks. For teams running browser compatibility checklists, this reduces the need for long-lived fallback branches.
The downside: browser release notes now arrive twice as often, and keeping your team's compatibility matrix current requires more frequent review. Automated tooling like Can I Use and Browserslist update their data accordingly, but manual documentation processes will need a faster cadence too.
The New Schedule at a Glance
As of September 2026, the major browsers ship on the following rhythm:
- Firefox — every two weeks. Firefox 155 shipped September 1; Firefox 156 on September 11; Firefox 157 expected September 25.
- Chrome — every two weeks. Chrome 153 shipped September 8; Chrome 154 expected September 22.
- Edge — follows Chromium's channel. Edge 152 shipped August 27; Edge 153 aligned with Chrome 153.
- Safari — continues shipping tied to OS and security update cadence; Safari 27 shipped September 14.
Safari remains the outlier — Apple ties browser releases to OS updates and security patches rather than a fixed calendar, which has always made its schedule harder to predict. For the three Chromium/Gecko engines, however, the alignment is now the tightest it has ever been.
For the full announcement from Mozilla, see the gHacks coverage of Mozilla's July 2026 announcement.