Tox is a communications protocol behind the Tox instant messaging client. Alternative implementations of this protocol are around, such as Xot, but not widespread.

Protocols
Anonymity
I2P
Tor
Communication
DNS
IRC
Matrix
Tox
XMPP
Encryption
GPG
OMEMO
OTR
S/MIME
SSL/TLS
ZRTP
Synchronization
ActiveSync
CalDAV
CardDAV
WebDAV
Syndication
RSS