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Signal vs Simlar: catalog facts
Signal	Simlar
Free Free; developed by a nonprofit funded by grants and donations	Free Free and open source under the GPL.
Android, iOS, Windows, macOS, Linux	Android, iOS
End-to-end encryption on every message and call using the open source Signal Protocol No ads, affiliate marketers or tracking	Encrypts calls with ZRTP Verifies contacts with a short code on the first call
Requires a phone number that can receive an SMS or phone call to register Desktop app requires Signal to be installed on a phone first	Both callers need to be online Call quality depends on the internet connection
Downloadable app	Downloadable app
Open source	Open source
License: AGPL-3.0	License: GPL-2.0-or-later
Account needed	Not stated if an account is needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 20, 2026	Official website Full listing and sources Checked October 8, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.