Instant messaging services

Name Decentralized Registration requirements Client Backend End-to-end encryption Summary
Discord No E-mail, username, date of birth Proprietary (use their web app if you are forced to use it) Proprietary No If you sing up from TOR it will ask you for your mobile number. Spyware for the cattle, avoid it at all cost.
Facebook Messenger No E-mail or phone number, first name, last name, date of birth, gender Proprietary (use their web app if you are forced to use it) Proprietary No Made by Meta (Facebook), spyware for the cattle, avoid it.
WhatsApp No Phone number, first name, last name Proprietary (use their web app if you are forced to use it) Proprietary They claim it's end-to-end encrypted Owned by Meta (Facebook), spyware for the cattle, avoid it.
Telegram No Phone number, first name GPL-2.0 / GPL-3.0 and more Proprietary They claim it's end-to-end encrypted Avoid it
Signal No Phone number, first name AGPL-3.0 / GPL-3.0 AGPL-3.0 Yes Avoid it if you can
XMPP Yes Username Many Many Yes Recommended
Matrix Yes Depends on your homeserver but a username is enough Many Many Yes Recommended but avoid using the matrix.org homeserver
GNU Jami Yes None, randomly generated account ID GPL-3.0 GPL-3.0 Yes Recommended
IRC No Username Many Many No Recommended
Tox Yes None, randomly generated account ID Many Many Yes Recommended
Session Yes None, randomly generated account ID GPL-3.0 GPL-3.0 Yes Recommended