Slack alternatives

6 open source tools you can use instead of Slack

The most-starred open source alternative to Slack is Rocket.Chat. Other notable options: Mattermost, Zulip, Lark CLI, OpenIM. All of them are free to download and most can run on your own server.

Rocket.Chat46.4k

RocketChat/Rocket.Chat

Self-hosted secure team communication platform with chat, video calls and omnichannel customer support.

Alternative to: Slack

LicenseOpen source

CategoryCommunication & SocialSelf-hosted

LanguageTypeScript

Last updatetoday

PlatformsWebDocker

Mattermost39.5k

mattermost/mattermost

Open source platform for secure team messaging and collaboration that you can run on your own server.

Alternative to: Slack

LicenseOpen source

CategoryCommunication & SocialSelf-hosted

LanguageTypeScript

Last updatetoday

PlatformsWebDocker

Zulip26.2k

zulip/zulip

Open source team chat with topic-based threading, an alternative to Slack.

Alternative to: Slack

LicenseOpen sourceApache-2.0

CategoryCommunication & SocialSelf-hosted

LanguagePython

Last updatetoday

PlatformsWebAndroidiPhoneDocker

Lark CLI18k

larksuite/cli

Official command line tool for Lark/Feishu to work with messages, documents and calendars from the terminal.

Alternative to: Slack

LicenseOpen sourceMIT

CategoryProductivity & Notes

LanguageGo

Last updatetoday

PlatformsCommand line

OpenIM16.8k

openimsdk/open-im-server

Self-hostable open-source server that adds instant messaging and group chat to your own apps.

Alternative to: Slack

LicenseOpen sourceApache-2.0

CategoryCommunication & SocialSelf-hosted

LanguageGo

Last updatetoday

PlatformsLinuxDocker

Element Web13.6k

element-hq/element-web

Glossy web client for the Matrix network for chat and collaboration

Alternative to: Slack, Discord

LicenseOpen sourceAGPL-3.0

CategoryCommunication & SocialSelf-hosted

LanguageTypeScript

Last updatetoday

PlatformsWebDocker