Slack is one of the most popular team communication services for work. Some may call it a glorified IRC but that doesn’t impact its popularity.
It is available for free with additional features offered in its paid plans. Though Slack can be installed on Linux thanks to an Electron app but it is not open source, neither the client nor the server.
In this article, I’ll list a few open source Slack alternatives that you can try.
Slack Alternatives Software That Are Open Source
The software mentioned here are open source which means you could install them on your own server (self-hosting) and thus control the data.
You may also opt to pay for the managed hosting for some of these Slack alternatives. A few of them provide both free and paid options.
That’s how some open source projects make money. You can take the trouble of hosting it on your own or pay for a hosted service offered by the project itself.
Let’s take a look at what options do you have to replace Slack and Microsoft Teams.
Note: The list is in no particular order of ranking.
1. Riot
Key Highlights:
- Decentralized Communication
- Cross-platform support
- Built on Matrix
- Self-hosting supported
- Third-party integrations supported
- Free and paid options available for managed hosting
While Riot has been a decent Slack alternative since its first stable release, it offers a lot of essential features that most of the Slack users can utilize. You can choose to use the public Matrix servers for free or the premium hosted servers.
To start with, you get cross-platform support, so once you’ve set up your own server (or by using the free public server), all you have to do is create rooms/communities. Rooms are like the channels and the communities act as a new group/server.
Everything should work flawlessly ranging from sending messages to attaching files. However, you might find it tricky to enable the end-to-end encryption for the room you’re joined in. You may refer to the official FAQ docs available.
Simply follow the official installation instructions to get started. There’s a lot more to explore, try it out!
2. Zulip Chat
Key Highlights:
- Advanced threaded conversation
- Self-hosting supported
- Integration support with Matrix
- Third-party integrations that include GitHub as well
- Cross-platform
- Free and paid options available
Zulip Chat is a good open-source team chat software.
Not just limited to the open-source enthusiasts, but Zulip Chat offers some really useful features when compared to Slack in general. The threaded conversations with the ability to filter by topics is a plus. So, you can just join back to a conversation that was hours ago before scrolling down hours of gibberish messages that weren’t probably meant for you in a channel.
The UI may not be as good as Slack but it is good enough for most of the users. You can either choose to install Zulip on your server or use Zulip’s hosted solution for free with limitations (or upgrade it to unlock features). You can also take a look at their GitHub page to learn more.
3. Rocket.Chat
Key Highlights:
- Cross-platform
- User support helpdesk integration support
- Real-time translation
- Audio/Video conferencing
- Third-party integrations
- Self-hosting supported
- Free and paid options available
Rocket.Chat is also an impressive Slack alternative that you can choose for your work or organization. In fact, we are considering to use it for our internal team communication at It’s FOSS.
The user interface is quite good and you can choose to customize the look of it by creating your own theme packages. In addition to all the essential features that Slack offers, it also supports video/audio conferencing, which is very important to some. You can host it yourself with limited features for free or opt for premium cloud hosting options.
Using end-to-end encryption with Rocket.Chat is a one-click task as well. Personally, I like the user experience better when compared to the others in the list – but that’s just me. You can also follow their active GitHub page to know more about it.
4. Mattermost
Key Highlights:
- Cross-platform
- Tailored mostly for enterprise use
- Free and paid options
- Real-time group chat
- Third-party integration
- Self-hosting supported
- UI/UX Customization supported
Unlike others, Mattermost is an enterprise-focused Slack alternative. You wouldn’t be too surprised that you may not like to use it for personal use.
You can opt to deploy the open-source edition for free but you will be limited to the free features. So, it is highly likely that you have to request a trial key before purchasing the license for Mattermost.
For obvious reasons, you won’t be able to try anything on your desktop unless you have a trial key because the demo is limited to their online website as a temporary session. Unless you’re an enterprise who needs something very similar to Slack but open-source, I don’t think you’d need this. If you’d like, you can also take a look at their GitHub page.
5. Wire
Key Highlights:
- Cross-platform
- No free options (30-day Trial offered)
- Text, voice and video chats
- Privacy-focused
- Self-hosting option available for Enterprise
We’ve already covered Wire as an alternative to Slack in one of our previous articles. It is indeed a useful open-source solution that focuses on privacy while giving a premium UX for users looking to switch from Slack.
You would need to opt for the Enterprise-focused premium plan if you want a custom deployment for Wire. You can try the hosted pro version (Desktop/Mobile) for free up to 30 days but for a private hosting deployment, you need to contact them.
You can learn more about it on their GitHub page or simply visit the official website through the button below.
Wrapping Up
Slack is unquestionably a good team chat app, but if you want to stick with open source solution, you can try one of these recommendation.
I’d recommend you to re-read the key highlights mentioned for each of the apps mentioned to help decide for yourself.
Feel free to try them and let me know your thoughts in the comments. Also, if I missed something that’s potentially an open source Slack alternative, let me know!