Open Source Slack Alternatives

    Slack is described as 'Real-time messaging, archiving and search for modern teams to stay focused and productive'. There are more than 100 alternatives to Slack for various platforms. The best alternative is Mattermost, which is both free and Open Source. Other great apps like Slack are Element (Freemium, Open Source), Zulip (Free Personal, Open Source), Rocket.Chat (Freemium, Open Source) and Matrix.org (Free, Open Source).

    The list of alternatives was last updated May 12, 2021
    Slack info, screenshots & reviewsAlternatives to Slack
    • 204 alternatives
    •  39 showing

    • Mattermost

      Mattermost is an open source, self-hosted Slack alternative. View 122 alternatives to Mattermost
      Almost everyone thinks Mattermost is a great alternative to Slack.
      • Freemium • Open Source
      • Mac
      • Windows
      • Linux
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • JavaScript
      • Go (Programming Language)
      • Cloudron
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      Mattermost vs Slack
      pros, cons and recent comments
       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  about 2 years ago

      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

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

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

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

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

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

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      7 of 19 comments

    • Element

      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. View 239 alternatives to Element
      Almost everyone thinks Element is a great alternative to Slack.
      • Freemium • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • Matrix.org
      • Cloudron
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      Element vs Slack
      pros, cons and recent comments
       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  about 3 years ago

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

      Privacy by design and based on matrix protocol!
      Positive comment • 5 months ago

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

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

      User6044478 decentralised, federated, end-to-end encrypted communication.
      Positive comment • over 3 years ago

      Free and opensource with better performance and features for team communication.
      Positive comment • over 3 years ago

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      7 of 9 comments

    • Zulip

      Zulip is a group chat app in which messages are threaded by topic, helping you have long-running, organized conversations. View 229 alternatives to Zulip
      Almost everyone thinks Zulip is a great alternative to Slack.
      • Free Personal • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • BSD
      • iPad
      • Self-Hosted
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      Zulip vs Slack
      pros, cons and recent comments
       all • positive • negative      relevance • date
      abijith Three reasons: 1. Open source. 2. Stream 3. Topics
      Top positive comment  over 3 years ago

      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  about 2 years ago

      the threading model is the best i've used for keeping up with active communities, and the open-source community is excellent.
      Positive comment • 6 months ago

      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 • 6 months ago

      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

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

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

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      7 of 16 comments

    • Rocket.Chat

      Rocket.Chat is a Web Chat Server, developed in JavaScript, using the Meteor fullstack framework. View 117 alternatives to Rocket.Chat
      Almost everyone thinks Rocket.Chat is a great alternative to Slack.
      • Freemium • Open Source
      • Mac
      • Windows
      • Linux
      • Self-Hosted
      • Cloudron
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      Rocket.Chat vs Slack
      pros, cons and recent comments
      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

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

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

    • Matrix.org

      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... View 120 alternatives to Matrix.org
      Most users think Matrix.org is a great alternative to Slack.
      No screenshots yet
      • 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.org vs Slack
      pros, cons and recent comments
      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

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

      somegirlfromit Matrix is a protocol, not a client.
      Top negative comment  over 1 year ago

      User6044478 Open source, fecentralized, federation, chat-voice-video function.
      Positive comment • over 3 years ago

      Free open source instant messaging service with federation.
      Positive comment • over 3 years ago

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

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

    • Jitsi

      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! View 204 alternatives to Jitsi
      Some users think Jitsi is a great alternative to Slack, some don't.
      • Free • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • BSD
      • iPad
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      Jitsi vs Slack
      pros, cons and recent comments
      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 • 11 months ago

    • Wire

      Wire is the most secure collaboration platform featuring messenger, voice, video, conference calls, file-sharing, and external collaboration –all protected by the most secure... View 251 alternatives to Wire
      Most users think Wire is a great alternative to Slack.
      • Free Personal • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
      • Android Tablet
      • iPad
      • Self-Hosted
      • Software as a Service (SaaS)
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    • Conversations

      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]. View 144 alternatives to Conversations
      • Free • Open Source
      • Android
      • Android Tablet
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    • Threema

      A secure, end-to-end encrypted Swiss instant messenger with a focus on privacy. View 89 alternatives to Threema
      No screenshots yet
      • Online
      • Android
      • iPhone
      • Android Tablet
      • iPad
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    • Gitter

      Gitter is a chat and collaboration tool for developers and users. It's a place for developers to talk. View 49 alternatives to Gitter
      Most users think Gitter is a great alternative to Slack.
      • Free • Open Source
      • Mac
      • Windows
      • Linux
      • Online
      • Android
      • iPhone
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    Showing 10 of 39 alternatives