The IdentitySwitcher is a simple and useful tool to allow you to switch between users, without knowing their passwords.
This is an excellent tool to use during development and testing. Place the module in the toppane of every page and login in as a different users is just one click away. Test functionality of your site for the various users.
It is even possible to switch to a host user, when allowed by the host account in the settings of the module.
Remove the module before going live?
Credits: Original version created by ErikVB, look here