Ant is a Java-based, open-source tool that is provided by the Apache Foundation. It can be used to declare a sequence of build actions. It is well suited for both development and document builds. The toolkit ships with a copy of Ant.

DITA-OT uses Ant to manage the XSLT scripts that are used to perform the various transformation; it also uses Ant to manage intermediate steps that are written in Java.

The most important Ant script is the build.xml file. This script defines and combines common pre-processing and output transformation routines; it also defines the DITA-OT extension points.