Signal for Mac

Overview of Signal Private Messenger

Signal Private Messenger is a free, open-source chat and VoIP application built by the Signal Foundation — a nonprofit co-founded by Brian Acton (formerly of WhatsApp) and cryptographer Moxie Marlinspike. Interest in the app rose sharply after WhatsApp announced changes to its data-sharing practices with Facebook, prompting many users to look for more privacy-focused alternatives. Signal has been widely adopted since about 2018 and maintains an active security-minded community.

Security and privacy summary

Signal uses end-to-end encryption for messages and calls, so only the sender and recipient can decrypt the content of communications. Because of this encryption model, message contents are not accessible to the app’s servers, mobile carriers, or (in general) third parties. That level of protection is one reason journalists, government staff, and other people handling sensitive information choose it. The project is open-source, which allows independent experts to inspect the code and report bugs; the foundation argues this transparency improves security.

Notable capabilities

• Share photos, videos, links and voice recordings inside chats and calls.
• Create group conversations (the current maximum group size is roughly 150 members).
• Invite others to join via SMS, social links, or a direct invite URL.
• Lock the app using a passphrase or biometric authentication to keep conversations private from anyone with device access.
• Send messages that disappear after a chosen interval to limit how long content persists.
• Assign moderation rights for group conversations so admins can manage membership and content.
• Add an extra layer of account protection with two-factor authentication.
• Synchronize your contacts to discover who already has the app installed.
• Register with an alternate phone number (for example, a Google Voice number) if you prefer not to expose your primary number.
• On Apple devices, opt out of syncing Signal data to iCloud if you want to avoid backups stored in cloud services.

Things to keep in mind

• Open-source code: the app’s source is publicly viewable. That transparency helps external reviewers find and report vulnerabilities, but it also means experts can study the implementation in detail.
• Comparable protections elsewhere: other messaging platforms (e.g., Apple Messages, Telegram, WeChat) offer some privacy or security features, so consider the full trade-offs and threat model when choosing a messenger.
• Feature trade-offs: Signal focuses on privacy and security rather than cosmetic extras, so it has fewer options for stickers, themes, or extensive customization compared with some mainstream apps.

Practical suggestions for users

• Enable app locking (passcode or fingerprint) to prevent access by people who have your phone.
• Turn on disappearing messages for conversations you don’t want to persist.
• Use a secondary number if you need to keep your primary phone number private.
• Review and disable cloud backups (iCloud on iOS) when you want to avoid storing Signal data in third-party cloud services.
• Keep the app updated and consider joining its security community or following announcements so you learn about fixes and improvements.