I was trying to implement Google logins last night for a site of mine. The documentation was hazy at times and Google wasn’t giving me any decent answers (and Stack Overflow was even more useless) so I came up with this which works: google-php.
It includes a sample page showing how to get information about a user from Google. Of course, I come back on this morning and did another search with a fresh head and found that Google have actually released their own official version: google-api-php-client. This API library is not linked from their documentation pages so you have to search Google for it with exactly the right term, I think I used “Google oauth logins php”.
I am however, sticking with mine since mine actually is smaller, simpler, and easier to use.
It is tailored specifically for website logins and is not really designed for long processing of output from a user API.