I'm aware that both Google and Facebook offer two-factor authentication, by sending an SMS to your phone under certain circumstances.

What other popular or high-profile web applications support two-factor authentication? I'd like to know which services I should turn on two-factor authentication for, since (at least for the two listed), it isn't the default.

  • I don't really understand why this was closed. It clearly pertains to web applications as per the FAQ. It's focused on users, not developers. And most of all, it's useful - it guides folks towards (potentially) more secure web applications, and could provide a useful checklist of apps to enable two-factor auth on. Can someone please clarify why it was closed? – Andrew Ferrier Aug 27 '12 at 23:04
  • Questions about polling or lists or subjective popular X for Y are off-topic for this site – phwd Sep 18 '12 at 14:28
  • Is there a way I can reword or rephrase this to make it more useful? – Andrew Ferrier Sep 18 '12 at 14:40
  • As of august 2012, Dropbox offers it too. – Alex Sep 18 '12 at 15:52
  • Amazon Web Services (AWS) supports two-factor authentication in the form of an RSA Token or using Google Authenticator
  • LastPass also offers two-factor login using Google Authenticator
  • PayPal offers two-factor SMS authentication

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