Sign in with Google or GitHub

The sign-in and sign-up pages have a Continue with Google button and a Continue with GitHub button above the email form.

Already signed up with an email and password? Sign in as usual, then connect Google or GitHub in Account, Security. The same page lists every browser signed in to your account, so you can sign one out, or all of them but this one. Highseat won't let you disconnect your last way to sign in.