Overleaf Git-Bridge and GitHub Synchronization features allow you to work on your LaTeX source offline, help you share with collaborators outside of Overleaf, and allow you to integrate Overleaf into more complex workflows.
Getting Started:
Lists of references in LaTeX projects are usually stored in a .bib file which is then referenced in then main .tex file. Here are the most common packages used to work with bibliographies in LaTeX
Using Mendeley and Zotero with Overleaf:
Using EndNote and RefWorks with Overleaf:
Using Paperpile with Overleaf:
Grammarly
Grammarly can be used with Overleaf. Simply install the Grammarly browser extension (you will need to make a Grammarly account if you don't already have one). You may want to switch off Overleaf's default spell checker if you are using Grammarly. For information about performance issues and limitations, see Overleaf's how-to page for Grammarly.