Whisper Systems produces security and privacy software applications for mobile communications devices running the Android operating system, including WhisperMonitor, Flashback, WhisperCore, RedPhone, and TextSecure. The software is thought to have played a key role in helping Egyptian democracy activists communicate during the early 2011 Middle Eastern events which have since become known as the Arab Spring.

On 28 November, 2011, Twitter announced that it will acquire Whisper Systems for an undisclosed amount, rumored in part to acquire Moxie Marlinspike

Moxie Marlinspike

Moxie Marlinspike is a computer security researcher. He has discovered several high-profile computer-related security problems, is well known for work with both secure protocols and Android, and is the author of the sailing film Hold Fast....

's security expertise.