Encrypted Messaging and Calls

Briar: A peer-to-peer messaging app for activists, offering offline communication via Bluetooth or Wi-Fi with end-to-end encryption (Briar).
Cellcrypt: A secure communication platform for encrypted voice and messaging, designed for enterprise use (Cellcrypt).
Criptext: An encrypted email and messaging service using the Signal Protocol for secure communication (Criptext).
Dust: A private messaging app with disappearing messages and end-to-end encryption, ideal for sensitive communications (Dust).
Goldbug: A decentralized social network with encrypted chat, email, and file transfers, emphasizing strong multi-encryption (Goldbug).
Hyperboria: A decentralized social network built on GNUnet, offering privacy-focused messaging and social features (Hyperboria).
Matrix (Element): A decentralized, open-standard platform for secure messaging, voice, and video calls with end-to-end encryption (Element).
Seecrypt: A secure communication tool for encrypted phone calls and messaging, designed for high-security needs (Seecrypt).
Session: A decentralized messaging app with end-to-end encryption, offering private calls (in beta) and no central servers (Get Session).
Signal: A leading app for end-to-end encrypted messaging and calls, trusted for its open-source security (Signal).
Silent Phone: An enterprise-grade app for encrypted voice, video, and messaging, actively supported by Silent Circle (Silent Phone).
Telegram: Offers encrypted secret chats for messaging, though default chats lack encryption, requiring user caution (Telegram).
Threema: A privacy-focused messaging app with end-to-end encryption, based in Switzerland, requiring no phone number for use (Threema).
Tox (Atox, QTox): A decentralized, peer-to-peer messaging protocol with encrypted clients like Atox (Android) and QTox (desktop) (Tox).
Wire: A secure messaging app with end-to-end encryption for messages, calls, and file sharing, suitable for personal and business use (Wire).