XACT (Cross-platform Audio Creation Tool) is an audio programming library and engine released by Microsoft as part of the DirectX SDK. It is a high-level audio library for authoring/playing audio that is written to use Xaudio on the Xbox, DirectSound on Windows XP, and the new audio stack on Windows Vista. Xaudio is an Xbox-only API designed for optimal digital signal processing. XACT also includes X3DAudio, a spatialization helper library available on both platforms, Windows and the Xbox. XACT was originally developed for Xbox development, and was later modified to work for Microsoft Windows development as well.

Support for XACT has been carried over from DirectX to XNA. The XACT Audio Authoring Tool is also available in XNA Game Studio Express.

The XACT Audio Authoring Tool is a companion application used to organize audio assets into wave banks (single files containing multiple WAV files) and sound banks (single files containing instructions for playing the WAV files in wave banks). The wave banks and sound banks for a project are subsequently called by XACT from within the application.