You probably use text message, Facebook Messenger, WhatsApp, or even Instagram to chat with others. And while those messaging apps work fine, some still seek out alternatives that lean hard into a promise of security and privacy—like Signal.

The app has no ads, does not track users' data, and does not store any metadata such as timestamps, internet addresses or group names so it can't give them up if asked. It is considered one of the most secure systems in the world. A company called Whisper Systems created two encrypted apps, RedPhone for voice calls and TextSecure for texting.