The latest version of the Firefox Alpha branch can be downloaded from Softpedia
Mozilla has officially announced that the second release in the Firefox 23.x branch is now available for download on the Linux platform.The Linux binaries for Mozilla Firefox 23.0 Alpha 2 have been made available and you can download it now, without having to install anything.
The new Firefox 23 Alpha 2 (Aurora) features mixed content blocking, consolidated search default preferences, better about:memory's functional UI, and a much more.
A detailed list of changes can be found in the announcement.
Download Firefox 23.0 Alpha 2 right now from Softpedia. Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.