Twilio Authy

Authy brings the future of two-factor authentication to the convenience of your iPhone or iPad.

The Authy app generates secure 2 step verification tokens on your device. It helps you protect your account from hackers and hijackers by adding an additional layer of security.

Why Authy is the best multi factor authentication app:

 - Secure Cloud Backups:
   Did you lose your device and get locked out of all of your accounts? Authy provides secure cloud encrypted backups so you will never lose access to your tokens again. We use the same algorithm that banks and the NSA use to protect their information.

 - Multi Device Synchronization:
   Are you re-scanning all your QR codes just to add them to your tablet and smartphone? With Authy you can simply add devices to your account and all of your 2fa tokens will automatically synchronize.

- Offline:
   Still waiting for an SMS to arrive? Do you travel constantly and lose access to your accounts? Authy generates secure tokens offline from the safety of your device, this way you can authenticate securely even when in airplane mode.

- All of your accounts:
  We support most major multi-factor authentication accounts including Facebook, Dropbox, Amazon, Gmail, and thousands of other providers. We also support 8 digit tokens.

- Protect your bitcoins:
   Authy is the preferred two factor authentication solution to protect your bitcoin wallet. We are the default 2fa provider for trusted companies like Coinbase, CEX.IO, BitGo and many others.

Official website:
https://www.authy.com