DiscourseAlternative toBettermodeOpen source forum and community platform, self-hosted47,998 GitHub starsGPL-2.0Licence GPL-2.0#Chat
ValourAlternative toDiscordOpen source Discord alternative with flexible community tools400 GitHub starsAGPL-3.0Licence AGPL-3.0#Chat
ProseAlternative toSlackDecentralized open source workplace with chat and docs59 GitHub starsMPL-2.0Licence MPL-2.0#Chat
AdaptAlternative toSlackLightweight self-hosted messaging platform for teams13 GitHub starsAGPL-3.0Licence AGPL-3.0#Chat
QuietAlternative toSlackPeer-to-peer serverless chat app with no central server2,659 GitHub starsGPL-3.0Licence GPL-3.0#Chat
SpacebarChatAlternative toDiscordFree open source Discord reimplementation with full API parity2,210 GitHub starsAGPL-3.0Licence AGPL-3.0#Chat
RevoltAlternative toDiscordSelf-hosted open source Discord alternative with servers3,406 GitHub starsAGPL-3.0Licence AGPL-3.0#Chat
MatrixAlternative toSlackOpen protocol for secure, decentralized messaging and VoIP4,716 GitHub starsAGPL-3.0Licence AGPL-3.0#Chat
ElementAlternative toSlackSecure team chat built on the Matrix open protocol13,601 GitHub starsAGPL-3.0Licence AGPL-3.0#Chat
ZulipAlternative toSlackOrganized team chat with threaded conversations, self-hostable26,085 GitHub starsApache-2.0Licence Apache-2.0#Chat
ToxAlternative toThreema WorkFree encrypted P2P messaging and voice calls, no servers2,696 GitHub starsGPL-3.0Licence GPL-3.0#Chat
Microsoft Teams
Discord
