Windows, Mac and Linux editions of Firefox 21 can be downloaded manually from Mozilla's site; already installed copies will upgrade automatically. Users of Firefox for Android can retrieve the update from the Google Play store.
The next version of Firefox is scheduled to ship June 25.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is firstname.lastname@example.org.
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