system_plugins is a config setting in tiddlywebconfig.py that lists the plugins which are configured for the running TiddlyWeb server. Another setting twanager_plugins lists those plugins which add functionality to the twanager command line tool. Some plugins need to be listed in both.

The value of the config item is a Python list of strings. Each string is the name of a Python package or module located either in the instance directory or somewhere on Python's sys.path.

At server startup time the modules are found, compiled, and the function init(config) is called on them, with a reference to the current config being passed in. Use this to add functionality to the server that cannot be accomplished from the defaults, such as adding additional web handlers, storage hooks or overriding existing behaviors.