Firefox expands sidebar and vertical tabs experiment to stable builds

Mozilla is bringing its sidebar and vertical tabs experiment to more users, rolling it out to stable versions of Firefox. After testing the feature in Nightly builds earlier this year, the team is now experimenting with it in Firefox releases 133 and 134. But not everyone will see it right away. Only a portion of users will be included in this phase to gather feedback and make improvements.

The updated sidebar lets you manage bookmarks, extensions, and synced tabs from your mobile device in one place. Vertical tabs, on the other hand, make multitasking easier by stacking tabs on the side instead of cramming them into a horizontal bar. This design feels especially handy for users juggling a lot of tabs. Here’s a video highlighting what to expect with the new vertical tabs and sidebar:

Mozilla isn’t stopping at just introducing the features — they’re also fine-tuning them based on feedback:

• Adding easier ways to close tabs in the collapsed sidebar.
• Allowing the sidebar to expand when you hover over it.
• Reducing the space taken up by sidebar tools in expanded mode.
• Polishing the overall look and usability of the sidebar and vertical tabs.

If these updates feel half-baked, Mozilla gets it. They’ve made it easy to opt out of the experiment via about:studies or disable the features in the sidebar settings.

If you’re lucky enough to be part of the experiment, you’ll get a nudge to enable the features. For now, there’s no manual way to jump in unless you were already testing it in Nightly builds. To check if you can use this experimental feature, go to Settings > Firefox Labs > Toggle on the Sidebar and Vertical tabs features. To complete the setup, access the toolbar’s context menu with a right-click, select Customize toolbar, and then move the sidebar control to your preferred position on the toolbar. Once added, this icon gives you quick access to expand your tabs vertically.

The experiment feels like Mozilla’s way of saying, “We hear you.” Vertical tabs and sidebars have been among the most requested features by the Firefox community. If all goes well, we could see these features become a permanent part of Firefox in future updates.

So, are you ready to embrace the vertical life? Or will this be another feature you disable and forget about? Let us know in the comments below.