JO's Google Auth is an extension for Joomla that allows you to log in to your account Google which is "mapped" to a user account Joomla
It takes the form of three extensions:
- com_jogoogleauth that interfaces with Google's aurhentification APIs
- plg_jogoogleauth that adds a google login button to mod_login modules
- mod_jogoogleauth which is a separate module that only allows to connect to Google
I maintain the source code on 
Github/jogooglecode which is compatible Joomla 5.x
User :