One of the main features of Overleaf is the ability to share projects and collaborate on them with other users.
"Link Sharing" allows a project owner to share their project via secret links. Anyone who has one of these secret links to a project will be able to view and/or edit the project, depending on the type of link used.
To let someone access the project, simply send them the URL of the project. Note that users must have an Overleaf account to edit a link-shared project.
Sharing a project with named collaborators is more powerful, as the only people who will be allowed to access the project are people who you have invited to collaborate on the project. To share a project with someone:
Your collaborator will now receive an email inviting them to join the project. Once they have logged into their account, they will be able to accept the invite and collaborate on the project. The Share project window will update to show that they have accepted the request and joined the project. If they do not receive an email:
The number of collaborators you are allowed to invite will depend on the plan you are part of. See here to find out how many collaborators you are allowed, or to upgrade your subscription.