Signal is a messaging and calling app for Android and iOS, with desktop applications for Windows, macOS and Linux. It uses end-to-end encryption for conversations between Signal users, covering messages, shared media and calls. Messaging and calling are free, and the app has no advertising or trackers.
Usernames and phone number privacy
A Signal conversation can begin from a contact, a phone number or an exact username. Usernames let people send a message request without first exchanging phone numbers. They can be shared as text, a QR code or a link. After a request is accepted, the conversation shows the person’s profile name rather than treating the username as a permanent public handle.
Signal separates who can see your number from who can find you by it. By default, someone who does not already have your number saved will not see it in your profile details. You can also prevent people from finding your account through a number search, then share your username to establish contact.
There is no browsable username directory, so the other person needs the exact name or its shared link. Standard account registration still uses a phone number.
Media and files in chats
Chats carry text, recorded voice messages, photos, videos, GIFs and files over an internet connection. Stickers can also be sent, including packs users create and share themselves.
Disappearing messages
Signal’s disappearing messages put a retention timer on new messages. You can choose a timer for a particular chat or a default for new conversations, including a custom interval of up to four weeks. Changing the timer affects subsequent messages and synchronizes the setting with linked devices. It does not retroactively clear the chat’s older history.
The countdown starts when a message is sent on the sender’s device and when it is read on the recipient’s device. Once that device’s timer expires, Signal deletes the message from disk. A recipient can still keep a separate photograph or copy of the content.
Group administration
Group chats combine a shared conversation with a member list, group name, picture and description. Administrators can decide who may change group information and add people. They can also manage member requests and invitations, while removing members requires an administrator role.
Changes to the group’s details appear as alerts in the conversation, so members can see that the shared information has changed. Administrators can also restrict who changes the group’s disappearing-message timer.
Calls, call links and screen sharing
Signal supports individual and group voice or video calls. A reusable call link gives other Signal users a way to join without creating a new invitation for every meeting. The link’s creator can require approval before someone enters; while waiting, that person neither receives the conversation’s audio and video nor shares their own with the call.
On desktop, a participant can present an entire screen or one application window during a call. Only one person can present at a time, and the presenter’s camera video is hidden while the screen share is active.
Linking Signal Desktop to a phone
Signal Desktop connects to the account on a primary phone. An account can have up to five linked devices, and linking offers a choice to transfer the existing message history or start without transferring it. Synchronization can include all chats and the most recent 45 days of media.
The primary phone must come online at least once every 30 days to maintain those links. A linked device also becomes unlinked after 45 days of inactivity. The primary device’s linked-device list provides a place to review the connections associated with the account.
Secure Backups
Optional Signal Secure Backups automatically preserve an encrypted archive for restoring conversations after losing a phone, replacing it or reinstalling the app. The free plan includes text messages and the latest 45 days of media. A paid plan extends media storage to as much as 100 GB. View-once messages and messages due to disappear within the next 24 hours are excluded.
Restoration depends on a separate 64-character recovery key that Signal does not receive. Keeping that key is essential: the service cannot decrypt or restore the archive if it is lost.
