Signal's software is free and open-source.
The apps include mechanisms by which users can independently verify the identity of their contacts and the integrity of the data channel. Signal uses standard cellular telephone numbers as identifiers and secures all communications to other Signal users with end-to-end encryption. It can also be used to make one-to-one and group voice and video calls, and the Android version can optionally function as an SMS app. Users can send one-to-one and group messages, which can include files, voice notes, images and videos.
Signal is a cross-platform centralized encrypted instant messaging service developed by the non-profit Signal Technology Foundation and Signal Messenger LLC.
