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10 top picks · 2 audience rankings

Best open source team chat apps

The best open source team chat app is Rocket.Chat (MIT, 46,344 GitHub stars, Docker image). Novu stands out for a permissive MIT license, and Mattermost follows.

This page also breaks the picks down by team size and use: Rocket.Chat leads for startups, small business and enterprise.

Updated · data from GitHub, refreshed daily

Top picks

  1. Rank 1:

    Rocket.Chat

    RocketChat/Rocket.Chat

    Communications platform that puts data protection first (alternative to Gitter.im and Slack).

    Active · last commit Oct 28, 2026

    Team ChatTypeScriptDocker

    Stands out for the most GitHub stars. Rocket.Chat has 46,344 GitHub stars, uses the MIT license, ships a Docker image and had 2,486 commits in the last year; it replaces Slack and Discord.

  2. Rank 2:

    Novu

    novuhq/novu

    Notification infrastructure for developers.

    Active · last commit Oct 28, 2026

    Team ChatTypeScriptDocker

    Stands out for a permissive MIT license. Novu has 40,214 GitHub stars, uses the MIT license, ships a Docker image and had 2,467 commits in the last year.

  3. Rank 3:

    Mattermost

    mattermost/mattermost

    Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).

    Active · last commit Oct 28, 2026

    Team ChatTypeScriptDocker

    Mattermost has 39,455 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 2,155 commits in the last year; it replaces Slack.

At a glance

Open source team chat apps compared

Ranked on GitHub stars, commits in the last year, Docker images, open-source licenses and recent commits across the 38 apps in the team chat category. Projects with fewer than 12 commits in the last 12 months rank below every more active project.

Top 10 picks compared, data as of Oct 28, 2026
AppStands out forLicenseGitHub starsCommits (12 mo)Last commitDocker image
Rocket.Chatthe most GitHub starsMIT46,3442,486Oct 28, 2026Yes
Novua permissive MIT licenseMIT40,2142,467Oct 28, 2026Yes
Mattermost–AGPL-3.039,4552,155Oct 28, 2026Yes
Chatwootits Ruby codebaseMIT38,4671,509Oct 28, 2026Yes
ntfya permissive Apache-2.0 licenseApache-2.035,1261,243Oct 27, 2026Yes
OpenWA–MIT16,3286,682Oct 28, 2026Yes
Zulip–Apache-2.026,1255,128Oct 28, 2026No
Apprise–BSD-2-Clause17,659291Oct 25, 2026Yes
Fluxer–AGPL-3.010,6913,025Oct 27, 2026Yes
Gotify–MIT16,139282Oct 28, 2026Yes

1 of 3 · 10 picks

Top picks

10 of the 38 apps in the team chat category.

  1. 1

    Rocket.Chat

    Communications platform that puts data protection first (alternative to Gitter.im and Slack).

    Stands out for the most GitHub stars. Rocket.Chat has 46,344 GitHub stars, uses the MIT license, ships a Docker image and had 2,486 commits in the last year; it replaces Slack and Discord.

  2. 2

    Novu

    Notification infrastructure for developers.

    Stands out for a permissive MIT license. Novu has 40,214 GitHub stars, uses the MIT license, ships a Docker image and had 2,467 commits in the last year.

  3. 3

    Mattermost

    Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).

    Mattermost has 39,455 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 2,155 commits in the last year; it replaces Slack.

  4. 4

    Chatwoot

    Customer communication platform (alternative to Intercom and Zendesk).

    Stands out for its Ruby codebase. Chatwoot has 38,467 GitHub stars, uses the MIT license, ships a Docker image and had 1,509 commits in the last year.

  5. 5

    ntfy

    Push notifications to phone or desktop using HTTP PUT/POST, with Android app, CLI and web app, similar to Pushover and Gotify.

    Stands out for a permissive Apache-2.0 license. ntfy has 35,126 GitHub stars, uses the Apache-2.0 license, ships a Docker image and had 1,243 commits in the last year.

  6. 6

    OpenWA

    WhatsApp API gateway exposing messaging as REST endpoints, with a web dashboard, multi-account sessions, and webhook events (alternative to WhatsApp Business API providers).

    OpenWA has 16,328 GitHub stars, uses the MIT license, ships a Docker image and had 6,682 commits in the last year.

  7. 7

    Zulip

    Zulip is a powerful, open source group chat application.

    Zulip has 26,125 GitHub stars, uses the Apache-2.0 license and had 5,128 commits in the last year; it replaces Slack and Discord.

  8. 8

    Apprise

    Apprise allows you to send a notification to almost all of the most popular notification services available to us today such as: Telegram, Discord, Slack, Amazon SNS, Gotify, etc.

    Apprise has 17,659 GitHub stars, uses the BSD-2-Clause license, ships a Docker image and had 291 commits in the last year.

  9. 9

    Fluxer

    Instant messaging and VoIP platform built for friends, groups, and communities (alternative to Discord).

    Fluxer has 10,691 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 3,025 commits in the last year; it replaces Discord.

  10. 10

    Gotify

    Notification server with Android and CLI clients (alternative to PushBullet).

    Gotify has 16,139 GitHub stars, uses the MIT license, ships a Docker image and had 282 commits in the last year.

2 of 3 · 5 picks

Which open source team chat app is best for startups?

For startups, Rocket.Chat ranks first (MIT, 46,344 GitHub stars), followed by Novu and Chatwoot. Ranked for startups on GitHub stars, commits in the last year, Docker images, open-source licenses, project websites and recent commits.

  1. 1

    Rocket.Chat

    Communications platform that puts data protection first (alternative to Gitter.im and Slack).

    Rocket.Chat has 46,344 GitHub stars, uses the MIT license, ships a Docker image and had 2,486 commits in the last year; it replaces Slack and Discord. For startups it also scores on a Docker image, a permissive license (MIT), a project website and a commit in the last 90 days.

  2. 2

    Novu

    Notification infrastructure for developers.

    Novu has 40,214 GitHub stars, uses the MIT license, ships a Docker image and had 2,467 commits in the last year. For startups it also scores on a Docker image, a permissive license (MIT), a project website and a commit in the last 90 days.

  3. 3

    Chatwoot

    Customer communication platform (alternative to Intercom and Zendesk).

    Chatwoot has 38,467 GitHub stars, uses the MIT license, ships a Docker image and had 1,509 commits in the last year. For startups it also scores on a Docker image, a permissive license (MIT), a project website and a commit in the last 90 days.

  4. 4

    ntfy

    Push notifications to phone or desktop using HTTP PUT/POST, with Android app, CLI and web app, similar to Pushover and Gotify.

    ntfy has 35,126 GitHub stars, uses the Apache-2.0 license, ships a Docker image and had 1,243 commits in the last year. For startups it also scores on a Docker image, a permissive license (Apache-2.0), a project website and a commit in the last 90 days.

  5. 5

    Mattermost

    Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).

    Mattermost has 39,455 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 2,155 commits in the last year; it replaces Slack. For startups it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

3 of 3 · 5 picks

Which open source team chat app is best for small business and enterprise?

For small business and enterprise, Rocket.Chat ranks first (MIT, 46,344 GitHub stars), followed by Novu and Mattermost. Ranked for small business and enterprise (the same order for each) on GitHub stars, commits in the last year, open-source licenses and recent commits.

  1. 1

    Rocket.Chat

    Communications platform that puts data protection first (alternative to Gitter.im and Slack).

    Rocket.Chat has 46,344 GitHub stars, uses the MIT license, ships a Docker image and had 2,486 commits in the last year; it replaces Slack and Discord. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  2. 2

    Novu

    Notification infrastructure for developers.

    Novu has 40,214 GitHub stars, uses the MIT license, ships a Docker image and had 2,467 commits in the last year. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  3. 3

    Mattermost

    Platform for secure collaboration across the entire software development lifecycle, can be integrated with Gitlab (alternative to Slack).

    Mattermost has 39,455 GitHub stars, uses the AGPL-3.0 license, ships a Docker image and had 2,155 commits in the last year; it replaces Slack. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  4. 4

    Chatwoot

    Customer communication platform (alternative to Intercom and Zendesk).

    Chatwoot has 38,467 GitHub stars, uses the MIT license, ships a Docker image and had 1,509 commits in the last year. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

  5. 5

    ntfy

    Push notifications to phone or desktop using HTTP PUT/POST, with Android app, CLI and web app, similar to Pushover and Gotify.

    ntfy has 35,126 GitHub stars, uses the Apache-2.0 license, ships a Docker image and had 1,243 commits in the last year. For small business it also scores on a Docker image, an open-source license, a project website and a commit in the last 90 days.

FAQ

Questions and answers

Still curious? Email info@appsgit.com.

Is Rocket.Chat free?

Yes. Rocket.Chat is open-source software released under the MIT license, so you can self-host it at no cost. You only pay for the server it runs on, and some projects also offer an optional paid cloud plan.

Can I self-host these team chat apps with Docker?

Yes, 9 of the 10 picks. Rocket.Chat, Novu and Mattermost publish Docker images, so you can run them on a VPS or home server with Docker Compose. The others install from their own packages or source; follow each project's install guide.

Are all of these team chat apps open source?

All 10 apps on this list are open source. You can self-host and modify each one under its license.

Which of these team chat apps is the most actively developed?

OpenWA, with 6,682 commits in the last 12 months and a latest release, v0.26.0, from October 2026. Activity is a good sign that bugs and security issues get fixed.

How is this list ranked?

Ranked on GitHub stars, commits in the last year, Docker images, open-source licenses and recent commits across the 38 apps in the team chat category. Projects with fewer than 12 commits in the last 12 months rank below every more active project.

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