Signal

Signal uses the Signal Protocol, which encrypts each message and call on the sender’s device and decrypts it only on the recipient’s device, so no third party, including Signal, can read the content. The keys are generated locally and never leave the device, providing strong privacy protection.

Yes, Signal allows a primary phone number to be linked to a desktop or tablet app, but each secondary device must be approved by scanning a QR code from the primary phone. The secondary devices share the same encryption keys, and you can revoke access at any time from the phone settings.

Signal stores messages locally on each device and deletes them after a configurable period or when you manually remove them. Media files are saved in the app’s folder and can be cleared from settings. Because data stays on your device, storage usage depends on how much you send and receive.

Signal is completely free; there are no subscription fees, in‑app purchases, or advertisements for any feature, including one‑to‑one chats, group conversations, voice calls, or video calls. All functionality is provided at no charge, though standard data charges from your carrier may apply.

Signal does not offer built-in cloud backup, so you cannot restore chat history across devices without manually exporting it. It also lacks some social features like stories or extensive sticker libraries found in other apps. These trade‑offs prioritize privacy over convenience.