There are a number of free plugins you can use to extend the functionality of Zotero. Selected plugins will be featured on this page. For a complete list visit the Zotero page.
Zotero comes with a timeline feature, which allows users to visualize their Zotero libraries in various ways. It was created based on the SIMILE timeline tool from MIT. Information on creating timelines with Zotero is available on their website.
Zotfile is a free plugin available for Zotero that allows you to easily organize and rename article PDFs attached to your Zotero library.
Zotnet enables users to create a network map of the related items in their Zotero library.
A tool that allows users to do topic modeling with Zotero data. May not be compatible with the most recent version of Zotero.