Notes: The InterAx Editor and Player both require DirectX 8.1 (or newer) to be installed on the end-user's computer. DirectX is NOT included in the InterAx Editor Setup or the InterAx Support Setup.  While I do recommend that you include DirectX when distributing your game, realize that all computers come with DirectX, and many games come with DirectX.  Unless the end-user’s computer is extremely old and they don’t use it much, odds are that they already have DirectX 8.1 or newer installed.

License : Free from Microsoft

System Requirements: Please see the system requirements listed at Microsoft's website

Downloads: Click the link below to go to Microsoft's DirectX pages. There you should find a link to the latest version of DirectX.  You will be looking for the “End-User Runtime”.

http://www.microsoft.com/windows/directx/default.asp - Main DirectX information page