Instant messaging (IM)

wikipedia:IM

• Slack (2013)
• Internet Relay Chat (IRC)
• Jitsi (2003)
• Mattermost (2015)
• Matrix (client: Riot)
• Rocket.Chat (at least 2016)

• Zulip
• Keybase (open-source client with proprietary server)
• Wire (Open Source - End to End Encrypted)
• Gitter (2014)
• Discord (2015)

See also

• Instant messaging (IM), Messenger, Slack, Mattermost, RocketChat, Gitter, Discord, Microsoft Teams, Skype, Amazon Chime, Zoom, Google Chat, AWS Chatbot, LiveChat, APNs, Arattai, Zulip, Chanty, Fleep, Spaces, Zoho Connect, QQ, WhatsApp, Cliq, iMessage, Telegram