MaxIm DL has an open architecture that allows other programs to access its processing and imaging functions. You can also build a plug-in that appears on the menu. Plug-ins can use a mix of built-in MaxIm DL functions plus their own code to produce new capabilities.
Both freeware and commercial plug-ins are available from third parties. A partial list is available at https://www.diffractionlimited.com/maxim_extras.php
Source code for a very simple example plug-in is included with the MaxIm DL installation. For more information please see Image Processing Plug-In Modules.