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Signal vs Threema: catalog facts
Signal	Threema
Free Free; developed by a nonprofit funded by grants and donations	Paid A one-time purchase is required. Business plans are separate.
Android, iOS, Windows, macOS, Linux	Windows, macOS, Linux, Android, iOS, Web
End-to-end encryption on every message and call using the open source Signal Protocol No ads, affiliate marketers or tracking	No phone number or email required; the ID is random Apps are open source and the company is based in Switzerland
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	A one-time purchase is required for each platform Smaller user base than the mainstream encrypted messengers
Downloadable app	Downloadable app
Open source	Open source
License: AGPL-3.0	License: AGPL-3.0
Account needed	Not stated if an account is needed
Needs internet	Not stated if it works offline
Official website Full listing and sources Checked September 20, 2026	Official website Full listing and sources Checked September 22, 2026

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