Reference managers, or citation managers, are a genre of software that help researchers organize, annotate, share, and cite references during the research and writing process.
Mendeley, Zotero, and EndNote are three popular reference management applications, and they all offer a similar set of features. Selecting a reference manager is a personal decision and will come down to personal preference and cost.
The University of Wisconsin-Madison has created a comprehensive comparison of reference managers to help you decide which one is right for you.