Messenger Platform Phone Required Status
Briar
briarproject.org
Peer-to-peer messenger, no servers
MobileNoVerified
Element
element.io
Matrix protocol messenger
Mobile, Desktop, WebNoVerified
qTOX
qtox.github.io
Opensource P2P messaging client that utilizes the encrypted Tox protocol
DesktopNoVerified
Ricochet Refresh
ricochetrefresh.net
Anonymous messaging over Tor
DesktopNoVerified
Session
getsession.org
Anonymous messenger, no phone required
Mobile, DesktopNoVerified
Signal
signal.org
Open-source with strong encryption
Mobile, DesktopYesVerified