Sound-Proof, is a two-factor authentication mechanism that does not require interaction between the user and his phone.In Sound-Proof the second authentication factor is the proximity of the users phone to the device being used to log in. The proximity of the two devices is verified by comparing the ambient noise recorded by their microphones. Audio recording and comparison are transparent to the user. Sound-Proof can be easily deployed as it works with major browsers without plugins.With Sound-Proof we also implement different two-factor authentication mechanisms. Currently we enable the typical code-based approach that everyone is used to. In the future we will integrate novel and more two-factor authentication mechanisms.