Misago Users Online Plugin is a simple example plugin implemented using the plugin tutorial from Misago's developer documentation. It displays a list of online users on the categories page. This list is only visible to the forum administrators.
Please note that plugin's implementation of the online users feature is naive. This plugin will be a performance bottleneck if used on all but the smallest forums. This plugin is only shared as an example to for people interested in developing custom plugins.
GitHub: github.com/rafalp/misago-users-online-plugin
To install this plugin run git clone https://github.com/rafalp/misago-users-online-plugin.git in your Misago site's plugins directory and rebuild docker images (./appctl rebuild if you are using misago-docker).