Firefox 100 includes subtitle support for picture-in-picture video

The Android app also gains an HTTPS-only mode.

Thomas Trutschel via Getty Images

Following some concerns that it might break some websites due to the version number, Firefox 100 has arrived. While Mozilla hasn't exactly celebrated the milestone with massive updates, there are some useful new features for both desktop and mobile.

The desktop browser now has support for subtitles and captions when picture-in-picture mode is active. This is a welcome accessibility improvement for multitaskers, and one that users requested. PiP subtitles and captions will be initially available for YouTube, Netflix, Prime Video and sites that use the WebVTT format (such as Twitter and Coursera).

There's a new first-run language switcher feature too. When someone opens Firefox for the first time, it will check whether their device language is different from the browser's own default language. In that case, it will ask the user if they want to use one of more than 100 other languages as their default in Firefox. Meanwhile, the credit card autofill tool is now available in the UK, France and Germany. It was previously only active in North America.

On Android, there's now an HTTPS-only mode. That will automatically connect you to the HTTPS version of a website for increased security whenever possible. Mozilla added a similar feature to the desktop browser in 2020 and the Android version of its privacy-focused Firefox Focus browser in March. Other new Firefox mobile features include new wallpapers on both Android and iOS.

The latest version of the app offers clutter-free history and tabs on both platforms too. Duplicate sites will be removed from your history and items will be grouped (if you're looking for new shoes, for instance, all the options you looked at will be combined under the search term). There's also the option to search for things in your history too.

Tabs that haven't been opened in 14 days will be made inactive and moved out of immediate view, though you'll still be able to access them. Mozilla is bringing that feature to iOS after debuting it on Android last year.

The Firefox 100 features for desktop and Android are available now. They'll arrive on iOS later this week.