Signal Will Let You Sign Up Without a Phone Number — For $3

Deltachat and Jabber, both decentralized encrypted messaging apps (as opposed to Signal, which is centralized), don’t even require an email to create an account, let alone a phone number or payment.

Delta chat is also less secure than Signal because it runs on standard email servers, which inherently leak more tracking metadata (like sender and recipient addresses) and lack Signal’s advanced privacy features like Perfect Forward Secrecy.