Zotero is a free, open-source reference management software that allows users to organize research, cite sources, and share references. It works as a plugin with browsers to automatically capture citation data from websites. Users can tag, annotate, and attach files like PDFs to references. Zotero also has a web-based component that allows for syncing references across devices and collaborating in groups. While useful for managing citations, it has some limitations, such as an inability to search inside attached file contents other than PDFs.