The Best Open Source Slack AlternativesTop Group Chat Apps & Instant Messengers like Slack in 2023

The best open source alternative to Slack is Element. If that doesn't suit you, our users have ranked more than 100 alternatives to Slack and loads of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Slack are Mattermost, Zulip, Rocket.Chat and Wire.

Slack alternatives are mainly Group Chat Apps but may also be Encrypted Chat Apps or Instant Messengers. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Slack.

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Self-Hosted + Open Source

Slack

843

Freemium • Proprietary
Group Chat App

Slack is a unified communication platform built with an optimized workflow to keep modern teams focused and productive. A...

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Element
Is this is a good alternative?
Yes
No
Freemium • Open Source
Group Chat App
Instant Messenger
Encrypted Chat App
Mac
Windows
Linux
Online
Android
iPhone
Android Tablet
iPad
Self-Hosted
Matrix.org
Flathub
F-Droid
Cloudron
275 Element alternatives
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.
- - Element is the most popular Web-based, Windows, Android & Mac alternative to Slack.
- - Element is the most popular Open Source & free alternative to Slack.
Suggest and vote on features
Element Features
1. DecentralizedElement is based on a decentralized infrastructure with no single entity controlling it.
2. End-to-End EncryptionElement has E2E Encryption, for entire or parts of the app.
3. Privacy focusedElement is considered a privacy friendly alternative.
4. VoiP CallsElement allows you to make voice calls over Internet using the Voice over Internet Protocol (VoIP).
5. Dark ModeElement supports dark mode for comfortable usage in low light conditions.
6. Support for MarkDownElement supports MarkDown for document formatting.
7. File VersioningElement has a version system that lets you view and go back to older versions of the project/file/document.
8. No TrackingElement will not track you or use your personal data.
9. Real time collaborationMultiple users can work together in Element simultaneously.
Federated
Matrix Protocol
Voice Chat
Federation
Direct Messaging
Custom widgets
Simple installation
Clean design
Multiple languages
Per-room avatars
Comments about Element as a Alternative to Slack
Almost everyone thinks Element is a great Slack alternative.
all • positive • negative relevance • date
Tommi
It is decentralized and it works with an open standard
Top positive comment •
2

Guest
Federated, decentralized, encrypted, open-source.
Top positive comment •
5

Dserver Hosting
this is a open source and free software that is very useful for me
Positive comment •
1

kaspian
Encrypted, free, open-source, decentralized
Positive comment •
0

Guest
Privacy by design and based on matrix protocol!
Positive comment •
2

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5 of 12 comments
Mattermost
Is this is a good alternative?
Yes
No
Freemium • Open Source
Group Chat App
Encrypted Chat App
Team Collaboration Tool
Mac
Windows
Linux
Android
iPhone
Android Tablet
iPad
Self-Hosted
JavaScript
Go (Programming Language)
Cloudron
117 Mattermost alternatives
Mattermost is a secure, open source platform for communication, collaboration, and workflow orchestration across tools and teams.
Suggest and vote on features
Mattermost Features
1. Extensible by Plugins/ExtensionsMattermost can be extended with add-ons, plugins and extensions.
2. Built-in viewerMattermost shows you a quick preview of an image, page or file in supported formats.
3. Full-Text SearchMattermost lets you search for specific words or phrases from inside a document or database.
4. Support for @mentionsMattermost supports the use of mentions through @ to a particular user, who will be notified personally.
5. Support for MarkDownMattermost supports MarkDown for document formatting.
Chat Bot
On-premises software
Multi Channel
Webhook support
Supports XMPP
Plugin API
Data API
File Sending
Integrated File Sharing
Slack integration
Comments about Mattermost as a Alternative to Slack
Almost everyone thinks Mattermost is a great Slack alternative.
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 •
7

kostya
Allmost the same interface and features
Top positive comment •
3

Indiana Lake
Same with more emphasis on privacy.
Positive comment •
0

liger1978
Great interface, you control your data.
Positive comment •
0

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

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5 of 20 comments
Zulip
Is this is a good alternative?
Yes
No
Free Personal • Open Source
Group Chat App
Instant Messenger
Encrypted Chat App
Mac
Windows
Linux
Online
Android
iPhone
Android Tablet
BSD
iPad
Self-Hosted
223 Zulip alternatives
Zulip is the only modern team chat app that is designed for both live and asynchronous conversations. Zulip topics create a separate space for each discussion, so different conversations will never get in each other's way.
Suggest and vote on features
Zulip Features
1. Support for MarkDownZulip supports MarkDown for document formatting.
2. Syntax HighlightingZulip supports syntax highlighting for various programming and markup languages.
Threaded Conversations
Support for Hotkeys
Community-based
Integrated File Sharing
Chat Bot
GitHub integration
Secure Chat
Third party integrations
Chat organizer
Live topics
Comments about Zulip as a Alternative to Slack
Almost everyone thinks Zulip is a great Slack alternative.
all • positive • negative relevance • date
Paulo Coghi
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
Top positive comment •
3

Guest
the threading model is the best i've used for keeping up with active communities, and the open-source community is excellent.
Top positive comment •
2

Guest
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 •
2

Guest
The concept of topics to each message is a super useful feature :)
Positive comment •
3

Guest
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.
Positive comment •
4

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5 of 16 comments
Rocket.Chat
Is this is a good alternative?
Yes
No
Freemium • Open Source
Group Chat App
Encrypted Chat App
Team Collaboration Tool
Mac
Windows
Linux
Android
iPhone
iPad
Self-Hosted
Cloudron
129 Rocket.Chat alternatives
Rocket.Chat is a Web Chat Server, developed in JavaScript, using the Meteor fullstack framework.
Suggest and vote on features
Rocket.Chat Features
1. Ad-freeRocket.Chat doesn't contain any form of external advertising.
2. End-to-End EncryptionRocket.Chat has E2E Encryption, for entire or parts of the app.
3. Extensible by Plugins/ExtensionsRocket.Chat can be extended with add-ons, plugins and extensions.
4. Screen SharingYou can use Rocket.Chat to share your screen with your colleages or friends.
Omnichannel messaging
Channels
Self-Serve Capability
Telegram integration
Whatsapp integration
Bots
Integrated File Sharing
Video Conferencing
Chat Bot
Slack integration
Comments about Rocket.Chat as a Alternative to Slack
Almost everyone thinks Rocket.Chat is a great Slack alternative.
John Fastman
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 •
10

Guest
open source, locally hosted so you own your data.
Positive comment •
2

Guest
Rocket.Chat comes very close to slack regarding it's core features and handling.
Positive comment •
7
Wire
Is this is a good alternative?
Yes
No
Free Personal • Open Source
Group Chat App
Instant Messenger
Video Calling App
Mac
Windows
Linux
Online
Android
iPhone
Android Tablet
iPad
Self-Hosted
F-Droid
Software as a Service (SaaS)
262 Wire alternatives
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.
- - Wire is the most popular SaaS alternative to Slack.
Suggest and vote on features
Wire Features
1. End-to-End EncryptionWire has E2E Encryption, for entire or parts of the app.
2. VoiP CallsWire allows you to make voice calls over Internet using the Voice over Internet Protocol (VoIP).
3. Screen SharingYou can use Wire to share your screen with your colleages or friends.
4. Privacy focusedWire is considered a privacy friendly alternative.
5. Multiple Account supportWire support multiple accounts without the need to logout and login
Security focused
Encrypted calls
Voice Chat
File Sending
Voice messages
WebRTC
Private Chat
Secure Chat
Integrated File Sharing
Secure File Sharing
Opinions about Wire as a Alternative to Slack
Most users think Wire is a great Slack alternative.
Matrix.org
Is this is a good alternative?
Yes
No
Free • Open Source
Group Chat App
Instant Messenger
Encrypted Chat App
Mac
Windows
Linux
Online
Android
iPhone
Android Tablet
iPad
Self-Hosted
WebRTC
Python
JavaScript
Go (Programming Language)
Cloudron
Java
Perl
138 Matrix.org alternatives
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.
Suggest and vote on features
Matrix.org Features
1. DecentralizedMatrix.org is based on a decentralized infrastructure with no single entity controlling it.
2. End-to-End EncryptionMatrix.org has E2E Encryption, for entire or parts of the app.
3. Privacy focusedMatrix.org is considered a privacy friendly alternative.
4. VoiP CallsMatrix.org allows you to make voice calls over Internet using the Voice over Internet Protocol (VoIP).
5. Multiple Account supportMatrix.org support multiple accounts without the need to logout and login
6. Ad-freeMatrix.org doesn't contain any form of external advertising.
7. No TrackingMatrix.org will not track you or use your personal data.
8. Real time collaborationMultiple users can work together in Matrix.org simultaneously.
Federation
Distributed
Security focused
Spaces
Chat Bot
Voice Chat
Support for Multiple protocols
Server side history
WebRTC
Comments about Matrix.org as a Alternative to Slack
Almost everyone thinks Matrix.org is a great Slack alternative.
all • positive • negative relevance • date
nrg200
Capable of everything Slack can do, but can be self-hosted - keeping a team's data in-house.
Top positive comment •
1

Vladimir Studinsky
Open source, fecentralized, federation, chat-voice-video function.
Top positive comment •
1

somegirlfromit
Matrix is a protocol, not a client.
Top negative comment •
18

Guest
Respects your Freedom. Increasingly popular
Positive comment •
2

Guest
Free open source instant messaging service with federation.
Positive comment •
0

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5 of 7 comments
Revolt
Is this is a good alternative?
Yes
No
Free • Open Source
Group Chat App
Instant Messenger
Video Calling App
Windows
Linux
Online
Android
Rust
Flathub
25 Revolt alternatives
Revolt is a brand new chat platform designed around you.
Suggest and vote on features
Revolt Features
1. Privacy focusedRevolt is considered a privacy friendly alternative.
2. Ad-freeRevolt doesn't contain any form of external advertising.
3. No TrackingRevolt will not track you or use your personal data.
4. VoiP CallsRevolt allows you to make voice calls over Internet using the Voice over Internet Protocol (VoIP).
5. Support for ThemesYou can use themes and templates to change the look and feel of Revolt .
6. Cloud SyncSync your data (notes, documents, bookmarks, etc.) across your different devices and to the cloud.
7. Screen SharingYou can use Revolt to share your screen with your colleages or friends.
8. Extensible by Plugins/ExtensionsRevolt can be extended with add-ons, plugins and extensions.
9. Support for @mentionsRevolt supports the use of mentions through @ to a particular user, who will be notified personally.
Text chat
Bots
Multiple Servers
Reactions
Custom roles
Cross-Platform
Voice Chat
Group Voice Chat
Multi Channel
Rust