Tab previews are in the works for a future release of Mozilla Firefox.

In current versions of Firefox you hover your mouse over a non-active tab (i.e. any tab other than the one you’re currently viewing) to see (after a small delay) a tooltip containing the web page title.

Handy, especially if you have a ton of open tabs, including several from the same site, and aren’t able to see enough of the page title in the tab itself to know which page is where.

But in the latest Firefox beta builds Mozilla developers are experimenting with a major enhancement in the form of tab previews.

When this feature is enabled, tab tooltips adopt a new ‘card’ design that shows a large thumbnail preview of each webpage, the website/webpage title, and the page URL:

Firefox tab hover thumbnail previews
Top: default tooltips; bottom: tab previews enabled

Firefox’s tab previews work with every tab except from the current/active one, including pinned tabs (where this feature could prove particularly useful given they only show a favicon).

As this flag/switch is not enabled by default in current Firefox beta builds we shouldn’t expect to find tab previews in Firefox 123 when it’s released as a stable update later this month.

But the fact Firefox devs are working on this feature is encouraging.

Other modern web browsers, including Google Chrome, Vivaldi, and Safari (though that’s not available on Linux) also show thumbnail previews when users mouse over non-active browser tabs.

It’s understandable that Firefox would wish to follow suit.

That said, some folks find these visually-rich tooltips distracting, so I hope Mozilla choose to include a toggle to disable tab previews in Firefox if — and for now it is still an ‘if’ — it decides to enable them by default in a future release.

Enable Tab Previews in Firefox 123 Beta

Firefox about:config showing tab experimental preview boolean switch
To try this out you need to set this switch to ‘true’

To try this experimental feature you need to have the latest beta build of Mozilla Firefox.

If you’re on Ubuntu you can install Firefox beta from Mozilla’s APT repo, download a binary from the Firefox website, or use the beta channel in the Snap Store.

Open Firefox Beta and:

  • Go to about:configin a new tab
  • Search for the browser.tabs.cardPreview.enabled flag
  • Double-click on the row to set it to true (or click icon at end of row)

Once enabled, you can use it; you don’t need to restart the browser.

If you don’t wish to see webpage thumbnails in the new tab cards you can disable them by changing the browser.tabs.cardPreview.showThumbnails switch to false.

To control how fast/slow tooltips appear modify browser.tabs.cardPreview.delayMs. This is set to 1000 (milliseconds) by default, meaning tooltips only appear once you’ve hovered over a tab for at least a second.