As expected, Mozilla kicked off the development of the next major Firefox release just one day after launching Firefox 52.0 as the new ESR (Extended Support Release) branch for GNU/Linux, macOS, and Microsoft Windows operating systems.

Yes, we're talking about Firefox 53.0, which received its first Beta build today, and it looks like the preliminary release notes have been published so we can share with you its upcoming features and changes. First off, you should know that the Mozilla Firefox 53.0 web browser is expected to launch next month on April 18.

As for the new features that could be implemented in the Firefox 53.0 release, we can mention the ability to apply lightweight themes in private browsing windows, support for the Reader Mode to display the estimated reading time for a particular web page, as well as the implementation of two new "compact" themes, one light and one dark.

These new themes appear to be based on the theme used in the Firefox Developer Edition web browser. For Windows users, Firefox 53.0 will allow them to choose between installing the 32-bit or 64-bit version directly from the installer. Talking about Windows, Firefox 53.0 won't be supported on Windows Vista, nor Windows XP.

Firefox 53.0 for Linux won't work on CPUs older than Pentium 4 or AMD Opteron

The bad news for Firefox users continues with the fact that the upcoming Firefox 53.0 release won't work on Linux computers powered by processors older than Pentium 4 or AMD Opteron, and 32-bit Mac OS X operating system won't be supported as Firefox is now distributed as a 64-bit only app for macOS Sierra or later.

Other noteworthy changes include automatic blocking of media playback on newly opened background tabs by default, redesigned media controls, smaller updates for macOS users, the addition of a fade-out effect for shortened titles on tabs to improve readability, and a cleaner design for permission notifications.

For web developers, Firefox 53.0 is bringing support for WebM video with alpha, enabling playback of videos with transparent backgrounds. If you want an early taste, we invite you to download Mozilla Firefox 53.0 Beta for GNU/Linux, macOS, and Microsoft Windows operating systems right now from our website.