Signal App

Signal is a cross-platform centralized encrypted instant messaging service developed by the non-profit Signal Foundation and its subsidiary, Signal Messenger LLC. It uses the Internet to send one-to-one and group messages, which can include files, voice notes, images, and videos. It can also be used to make one-to-one and group voice and video calls.

The app's development originally began with 'RedPhone' and 'TextSecure,' developed by Whisper Systems, which was founded by Moxie Marlinspike and Stuart Anderson. After Whisper Systems was acquired by Twitter, Marlinspike left and founded Open Whisper Systems to continue the development of TextSecure and RedPhone, which eventually merged into Signal. In 2018, the Signal Technology Foundation was formed with $50 million in funding from Brian Acton, the co-founder of WhatsApp.

Signal is widely regarded as one of the most secure communication platforms available because it employs end-to-end encryption via the Signal Protocol. As a non-profit organization, the company does not sell user data or use advertising, relying instead on grants and individual donations to sustain its operations.