Windows 8.1 build 9431

This is the client equivalent of Windows Server 2012 R2 Build 6.3.9431.winmain_bluemp.130615-1214

This build was released on 26/6/2013 with the occasion of //BUILD/ 2013 taking place. At first, the ISOs were only avaliable through TechNet & MSDN, while it was possible to download the Store version immediately after //BUILD/ began. The ISOs were made publicly avaliable the day after, on 27/6/2013.

Variants
The ISO version is avaliable in both x86 and x64. On TechNet you can only download English versions, the MSDN & public release is avaliable in 13 languages: Arabic, English (US), Chinese (Simplified), Chinese (Traditional), French, German, Japanese, Korean, Portuguese (Brazil), Russian, Spanish, Swedish, and Turkish. An RT version was also spotted in the wild, however the only way to install 8.1 on such a machine is throught the store and many users reported a "The update is not applicable to your computer." error.