Tool: Signal
Category: Encrypted Messaging
Platform: Android, iOS, Windows, macOS, Linux
Price: Free
Developer: Signal Foundation (nonprofit)
What It Does
Signal sends texts, voice calls, video calls, and file attachments with end-to-end encryption by default meaning only you and the person you’re messaging can read what’s sent, not Signal itself, not your carrier, not anyone intercepting the connection. It looks and works like any standard messaging app, but nothing is readable in transit or stored unencrypted on Signal’s servers.
The encryption protocol Signal built (the “Signal Protocol”) is so well regarded that WhatsApp, Google Messages, and Facebook Messenger all license or adapt it for their own encrypted chat features.
Key Features
- End-to-end encryption on everything messages, calls, video, and attachments, with no separate “secret chat” mode to remember to turn on
- Disappearing messages set chats to auto-delete after a set time
- Minimal metadata collection Signal deliberately stores as little about you and your contacts as it can, and publishes transparency reports about what little it does hold
- No ads, no data harvesting funded by a nonprofit foundation and donations, not by monetizing user data
- Cross-platform and desktop-linked full functionality on a computer, not just a stripped-down companion app
Why It’s on This List
Most people’s default messaging apps are not end-to-end encrypted, or only encrypt select chats you have to remember to enable. Signal makes strong encryption the default and the only option, with an open-source protocol that’s been independently audited and adopted industry-wide a rare case where the more private tool is also the free one.
Worth Knowing
- Both people need Signal installed for a conversation to be protected it can’t retroactively encrypt a chat with someone on SMS or WhatsApp
- A phone number is required to sign up, though Signal is testing ways to reduce reliance on it
- Backups are locally encrypted; losing your device and your backup passphrase together means losing chat history, by design
