Download .NET Framework 4.6: Web or Offline Installer
Microsoft has released the .NET Framework 4.6 Preview. Download the Web Installer or the Offline Installer by following these links:
Web Installer | Offline Installer.
The Microsoft .NET Framework 4.6 Preview is a highly compatible, in-place update to the Microsoft .NET Framework 4, the Microsoft .NET Framework 4.5, the Microsoft .NET Framework 4.5.1, and the Microsoft .NET Framework 4.5.2.
Microsoft has also updated the Term of the Microsoft Software License Agreement for the Microsoft .NET Framework 4.6 More details here.
Microsoft has already announced its plans to open source the entire .NET framework and made available Visual Studio Community Edition as a free download.
UPDATE 1: You can download the Microsoft .NET Framework 4.6 CTP 5 (Offline Installer) for Windows Vista SP2, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2008 SP2 Windows Server 2008 R2 SP1, Windows Server 2012 and Windows Server 2012 R2 HERE.
UPDATE 2: Microsoft .NET Framework 4.6 RC (Web Installer) is now available.
NOTE: More details about Microsoft .NET Framework 4.6 (Web Installer) for Windows Vista SP2, Windows 7 SP1, Windows 8, Windows 8.1, Window RT, Windows RT 8.1, Windows Server 2008 SP2, Windows Server 2008 R2 SP1, Windows Server 2012, and Windows Server 2012 R2 at KB3045560.