Plugins provide added functionality to Kst. By default, Kst comes packaged with an extensive selection of built-in plugins. In addition, a simple plugin API allows for easy creation of third-party plugins.

Kst plugins are usually comprised of an object file and a .desktop file. For plugins which are available system-wide the object and .desktop files should be stored in /usr/lib/kde3/ and /usr/share/services/kst/ respectively (this may vary depending on how your system is configured).