Doesn't work if you block third-party cookies

[games647]

Tested with Google (including YouTube), Twitter and Github.

If I allow third-party cookies, it shows that I'm logged in there (which is correct), but if I block third-party cookies it shows none of them. So this might be a way to work-around this too.

[derhuerst]

There might be a way to at least let users know that the tool doesn't work then. e.g. create a cookie on a different, but controlled, domain and then check.