Open Source Slack Alternatives

    The best open source alternative to Slack is Mattermost, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Slack and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Slack are Element (Free Personal, Open Source), Zulip (Free Personal, Open Source), Rocket.Chat (Freemium, Open Source) and Matrix.org (Free, Open Source).

    This page was last updated Jul 24, 2021

    1. Mattermost

      • Freemium • Open Source
      • Mac
      • Windows
      • Linux
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • JavaScript
      • Go (Programming Language)
      • Cloudron
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      Mattermost is an open source, self-hosted Slack alternative.
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      Mattermost vs Slack opinions
      Almost everyone thinks Mattermost is a great alternative to Slack.
       all • positive • negative      relevance • date
      shelehovchanin Same functionality. Same interface. At the same time, there are much fewer restrictions. IN my experience, the free version is great enough for a team of 100 people
      Top positive comment  over 2 years ago

      6
      Its the same but you keep your server where you want so no one is playing with your data, and you can have an unlimited history depending on what you need for free so really way better !
      Top positive comment  about 4 years ago

      3
      liger1978 Great interface, you control your data.
      Positive comment • about 1 year ago

      -1
      It's faster for one thing. It's far superior in terms of data ownership, and it's extremely scalable.
      Positive comment • over 1 year ago

      0
      svelle Has more flexibility due to its extensive plugin system compared to other alternatives.
      Positive comment • over 1 year ago

      0
      Mudie Looks and works very much the same as Slack and complete control over your data housed separately from anyone else.
      Positive comment • over 1 year ago

      0
      jaydeland Open source with control over your data.
      Positive comment • over 1 year ago

      -3
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      7 of 19 comments

    2. Element

      • Free Personal • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • Matrix.org
      • Cloudron
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      Element is a secure collaboration and messaging app based on the Matrix protocol. It’s decentralised to deliver digital sovereignty, and based on an open standard for easy connections and interoperability. It is end-to-end encrypted by default.
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      Element vs Slack opinions
      Almost everyone thinks Element is a great alternative to Slack.
       all • positive • negative      relevance • date
      brinerustle because its open source, decentralised, and end-to-end secure. Plus the folks at matrix.org are working to get us out of our communication silos by creating standards for communication interoperability!
      Top positive comment  over 3 years ago

      4
      Federated, free standard and free software
      Top positive comment  over 3 years ago

      3
      Privacy by design and based on matrix protocol!
      Positive comment • 8 months ago

      0
      Federated, decentralized, encrypted, open-source.
      Positive comment • about 2 years ago

      3
      User6044478 Open Source / Free Software,
      Positive comment • about 3 years ago

      0
      User6044478 decentralised, federated, end-to-end encrypted communication.
      Positive comment • almost 4 years ago

      7
      Free and opensource with better performance and features for team communication.
      Positive comment • almost 4 years ago

      3
      Show more comments ▾
      7 of 9 comments
    4. Zulip is a group chat app in which messages are threaded by topic, helping you have long-running, organized conversations.
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      Zulip vs Slack opinions
      Almost everyone thinks Zulip is a great alternative to Slack.
       all • positive • negative      relevance • date
      abijith Three reasons: 1. Open source. 2. Stream 3. Topics
      Top positive comment  over 3 years ago

      6
      Zulip is open source and the methods of communications used is vastly different. It is specially useful in professional environments where different teams might want to participate in different conversations at the same time. Zulip solves this problem by including topics, where in each channel/stream, multiple topics can exist at once, at the same time.
      Top positive comment  over 2 years ago

      3
      the threading model is the best i've used for keeping up with active communities, and the open-source community is excellent.
      Positive comment • 8 months ago

      1
      It's a little different, for sure, but what it does, it does better than slack. Not a open source copy of slack like mattermost. If you want slack and nothing else, but in open source, stick to mattermost, if you want something that exceeds that, choose zulip.
      Positive comment • 8 months ago

      1
      paulocoghi More than feature parity with Slack, it's better because of Streams and Topics. It offer the same free tier with 10.000 max messages and better paid plans to the hosted version, and also provide the open source self-hosted option to install it on your own server and also remove the max messages limits. 5 stars
      Positive comment • over 1 year ago

      2
      The concept of topics to each message is a super useful feature :)
      Positive comment • about 2 years ago

      2
      superbiche Open Source without limitations when on premises. Much better information categorisation with Streams & Topics. Vibrant community.
      Positive comment • over 2 years ago

      3
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      7 of 16 comments
    5. Rocket.Chat is a Web Chat Server, developed in JavaScript, using the Meteor fullstack framework.
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      Rocket.Chat vs Slack opinions
      Almost everyone thinks Rocket.Chat is a great alternative to Slack.
      JohnFastman Does everything Slack does AND it's open source. However, it's also self-hosted. This means you have to put in the effort to set it up, but you control your own data, which is a huge advantage to your privacy - your chats and files don't sit on someone else's servers, ready for them or hackers to look at.
      Positive comment • over 4 years ago

      8
      Rocket.Chat comes very close to slack regarding it's core features and handling.
      Positive comment • about 3 years ago

      4
      open source, locally hosted so you own your data.
      Positive comment • over 2 years ago

      0

    6. Matrix.org

      • Free • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • WebRTC
      • Python
      • JavaScript
      • Go (Programming Language)
      • Cloudron
      • Java
      • Perl
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      Matrix defines a set of open APIs for decentralised communication, suitable for securely publishing, persisting and subscribing to data over a global open federation of servers with no single point of control.
      No screenshots yet
      Matrix.org vs Slack opinions
      Most users think Matrix.org is a great alternative to Slack.
      It can be easily bridged to many other chat systems, including Slack, which makes transitioning *much* easier. It's also open source and decentralized (self-hostable + communication with other servers).
      Top positive comment  almost 4 years ago

      0
      Respects your Freedom. Increasingly popular
      Top positive comment  over 3 years ago

      0
      somegirlfromit Matrix is a protocol, not a client.
      Top negative comment  almost 2 years ago

      18
      User6044478 Open source, fecentralized, federation, chat-voice-video function.
      Positive comment • almost 4 years ago

      -1
      Free open source instant messaging service with federation.
      Positive comment • almost 4 years ago

      -1
      free, end-to-end encryption
      Positive comment • almost 4 years ago

      0
      nrg200 Capable of everything Slack can do, but can be self-hosted - keeping a team's data in-house.
      Positive comment • about 4 years ago

      -1
    8. Jitsi (previously SIP Communicator) is an audio/video and chat communicator with full encryption that supports protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, GTalk/Hangouts extensions, as well as OTR, ZRTP, etc.
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      Jitsi vs Slack opinions
      Some users think Jitsi is a great alternative to Slack, some don't.
      Jitsi is for video chat, slack is a team collaboration platform. In Slack, text messages are common, in Jitsi video chat is the main focus.
      Negative comment • about 1 year ago

      5

    9. Wire

      • Free Personal • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • Software as a Service (SaaS)
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      Wire is the most secure collaboration platform featuring messenger, voice, video, conference calls, file-sharing, and external collaboration –all protected by the most secure end-to-end-encryption. Why Wire?
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      Most users think Wire is a great alternative to Slack.
    10. Conversations is a privacy focused, open source XMPP Texting [Jabber] client for Android 4.0+ smart phones with wife-approved easy encryption [OTR, OMEMO, or GPG]. [Note] **You can download the compiled apk for free from F-Droid**: ...
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    11. Threema is a new mobile messaging app that puts security first. With true end-to-end encryption, you can rest assured that only you and the intended recipient can read your messages.
      No screenshots yet

    12. Gitter

      • Free • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
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      Gitter is a chat and collaboration tool for developers and users. It's a place for developers to talk. KEY FEATURES - Unlimited public chat rooms for free - Unlimited and searchable chat history - Unlimited integrations - Private chat rooms free up to 25 users
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      Most users think Gitter is a great alternative to Slack.
    Showing 10 of 42 alternatives