Firefox 21 arrives with social providers Cliqz, Mixi, MSN Now, open source fonts and HTML5 tweaks for Android

Mozilla on Tuesday officially launched Firefox 21 for Windows, Mac, Linux, and Android. Improvements include the addition of multiple social providers on the desktop as well as open source fonts on Android.

The new desktop version was available yesterday on the organization’s FTP servers last night, but that was just the initial release of the installers. Firefox 21 has now officially been released over on Firefox.com and all existing users should be able to upgrade to it automatically. As always, the Android version is trickling out slowly on Google Play.