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Signal vs Delta Chat: catalog facts
Signal	Delta Chat
Free Free; developed by a nonprofit funded by grants and donations	Free Free and open source under the GPL 3.0. Free chatmail relays are provided, or use any…
Android, iOS, Windows, macOS, Linux	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	Works with any email account, or with a provided chatmail relay Reaches people who do not use Delta Chat at all
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	Encryption only applies when the other side supports Autocrypt Email metadata such as subject and timing is visible to mail servers
Downloadable app	Downloadable app
Open source	Open source
License: AGPL-3.0	License: GPL-3.0
Account needed	No account needed
Needs internet	Works offline
Official website Full listing and sources Checked September 20, 2026	Official website Full listing and sources Checked September 21, 2026

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