Mendeley is an bibliographic management tool. An optional local client, Mendeley Desktop, synchronizes with a standard Web-accessible interface. Users can enter new references, generate references from hard drive directories, or find references that others have already entered. References can be tagged as required. The emphasis is on social collaboration and sharing. Users can associate with each other and groups can be formed to developed shared collections. Browser plug-in allows capture of reference information from just about any web page, and Mendeley has an API and plug-ins for word processors such as Open Office. PDFs can be uploaded from your local system, and citations can be generated and lists exported. Many online journals have one-click function to add a reference to your Mendeley library. There are limits on how many groups can be managed in the free-version.