Download Windows 8.1 Preview
Microsoft has released Windows 8.1 Preview today during its BUILD 2013 keynote and you can now download it for free. Windows 8.1 Preview has many new exciting features like a start button and more customization options.
It is available as an online installer which downloads Windows 8.1 Preview from the Windows Store and an ISO version in these languages: Arabic, English (US), Chinese (Simplified), Chinese (Traditional), French, German, Japanese, Korean, Portuguese (Brazil), Russian, Spanish, Swedish, and Turkish. If you want to install from ISO, you can use this product key: NTTX3-RV7VB-T7X7F-WQYYY-9Y92F
Keep in mind that it is a pre-release version and many contain many bugs.