Mendeley is a free reference management software package, also known as bibliographic software, which enables you to:
There is also a new add-in for MS Word, called Mendeley Cite, which can be used without the desktop app.
This Guide covers Mendeley Reference Manager, Mendeley Cite, Mendeley Web and Mendeley Desktop. (Mendeley Desktop will continue to be available until further notice.)
Mendeley have guidance on the new services: