Zotero is a free, easy-to-use research tool for collecting, organizing, annotating, citing, and sharing research materials. It serves as a personal research assistant, supporting automatic recognition and capture of research content while browsing the web, such as articles on JSTOR, preprints on arXiv.org, news from The New York Times, or books from a library. Users can organize their research in whatever way they like, categorizing items into collections and tagging them with keywords, or creating saved searches that automatically populate with relevant materials. Zotero can instantly create citations and bibliographies for any text editor, and integrates directly with Word, LibreOffice, and Google Docs. It supports over 9,000 citation styles and can match any style guide or publication requirement. Optional syncing can sync data across devices, keeping files, notes, and bibliographic records up to date; after syncing, research materials can also be accessed at any time from any web browser. Zotero also supports free collaboration, allowing a Zotero library to be shared with any number of people, making it easy to co-write papers, distribute course materials, or build a collaborative bibliography. Zotero is open-source software, developed by an independent nonprofit organization that has no financial interest in users' private information, and users always control their own data. Available for Mac, Windows, Linux, iOS, and Android. If you only need to quickly generate a bibliography, try ZoteroBib.