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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.

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closed as off topic by phwd Aug 27 '12 at 19:20

Questions on Web Applications Stack Exchange are expected to relate to web applications within the scope defined by the community. Consider editing the question or leaving comments for improvement if you believe the question can be reworded to fit within the scope. Read more about reopening questions here.If this question can be reworded to fit the rules in the help center, please edit the question.

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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Thanks, I didn't know about PayPal (although it looks like they've done it a dumb way: paypal-community.com/t5/Tips-from-Moderators/…). – Andrew Ferrier Aug 20 '12 at 12:10

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