The Plugin API lets you extend the File Uploader without forking or patching the library. Plugins can add upload sources, custom UI activities, per-file actions, file transformation hooks, icons, translations, and config options as a self-contained unit.
If you are starting from scratch, begin with Plugin structure & registration, then move to Extension points.
registerSource, registerActivity, registerFileAction, registerFileHook, registerConfigregisterIcon, registerL10npluginApi.config, pluginApi.activity, pluginApi.files