The Best Free Alternatives to Slack
Slack changed how teams talk, then built a pricing model that quietly punishes the exact thing that makes a chat tool useful: a long history and a growing team. The free alternatives now split into three camps — self-hosted open-source tools that replicate the Slack experience without the bill, topic-based systems that rethink the chat room from first principles, and decentralized options that free your team from any single vendor. The right choice depends on whether you want a drop-in replacement or a better model of team communication.
Illustration generated by Nexulab. Inline photo by Mikhail Nilov via Pexels
- If you want a self-hosted Slack replacement with channels, threads and integrations, Mattermost is the closest match: open source, free to run on your own server, and it looks and works like Slack without the per-user bill.
- If you want to rethink team chat instead of cloning it, Zulip threads every conversation by topic by default, so a busy team can read what matters without scrolling through a single noisy channel.
- If your team is drowning in always-on notifications, Twist is an async-first alternative where discussions are organised by thread and nothing interrupts you by default.
- If you want your team chat to be open to any client and any server, Element on Matrix is the decentralized route where you control the server and your data never has to live with a single vendor.
- No free alternative imports a Slack workspace with its full message history, files and integrations intact. The export exists, but the import is manual work, and it is worth knowing that before you commit the time.
Slack solved a real problem. Email threads were buried, IRC was hostile to newcomers, and team communication needed a home where channels, files and search lived together. Slack built that home, and for a while it felt like magic.
Then the bill arrived. Slack’s free tier limits how far back you can search your own message history, and its paid tiers scale per user, so the cost grows exactly as your team does. The tool that made a growing team feel connected is the same tool that charges more for that growth.
The free alternatives now split into three camps. Self-hosted open-source tools replicate the Slack experience — channels, threads, integrations — without the per-user bill. Topic-based systems rethink the chat room so conversations stay organised instead of piling into one noisy stream. And decentralized options free your team from any single vendor entirely. The right pick depends on whether you want to replace Slack or rethink team chat.
Self-hosted Slack replacements: Mattermost and Rocket.Chat
If you want Slack without the bill, two open-source projects come closest.
Mattermost is the most direct Slack replacement. It has channels, threads, direct messages, file sharing, search and a long list of integrations, and it runs on your own server with no per-user fee and no feature gates. If your team already knows how to use Slack, Mattermost requires almost no retraining because the layout and the concepts are the same. The trade-off is that you host it: you need a server, a domain, and the willingness to handle updates and backups. Mattermost also offers a free tier of its cloud edition, but the self-hosted version is where it shines.
Rocket.Chat covers the same ground with a slightly different emphasis. It has channels and threads like Slack, plus built-in video calls and a marketplace of integrations, and it can be self-hosted or used through its cloud. The self-hosted version is open source and free with no user limits, which makes it attractive for teams that want chat plus video in one place without juggling two subscriptions. The trade-off is that Rocket.Chat’s self-hosted setup asks a bit more of you during installation, and its interface feels busier than Mattermost’s deliberately calm clone of Slack.
Both are open source and free to self-host. Mattermost is the safer drop-in replacement for a team that wants Slack without the bill. Rocket.Chat is the better fit if you want chat and video calls in one self-hosted tool.
Topic-based rethink: Zulip and Twist
Slack’s model puts everything in a channel, and when a channel gets busy, the conversation becomes a single stream you have to scroll through to find anything. Two alternatives reject that model.
Zulip threads every message into a topic by default. Instead of one noisy channel, each subject gets its own thread, and people can follow the topics they care about and ignore the rest. For a team where several conversations happen at once — a support team, an open-source project, a busy engineering group — this changes the experience completely: you read what matters instead of scrolling past everything else. Zulip is open source, can be self-hosted, and has a generous free cloud tier.
Twist goes further and makes the tool async-first. Discussions are organised into threads, notifications are quiet by default, and nothing demands an immediate reply the way a live chat does. Twist is built for teams that find real-time chat draining and want the calm of a shared inbox organised by topic. The trade-off is that Twist is a hosted service, not self-hosted, so your data lives with the vendor and the free tier has its limits.
Zulip and Twist solve the same problem — the noisy chat room — from slightly different angles. Zulip keeps the live, fast feeling of chat while adding topics. Twist slows the whole thing down on purpose.
Decentralized: Element on Matrix
Element is a chat client that runs on Matrix, an open protocol for decentralized communication. The idea is that your team runs its own Matrix server — or joins a server run by someone else — and any Matrix client can connect to it. Your messages are not locked into a single vendor’s servers, and you can bridge to other services.
The appeal is ownership. A self-hosted Matrix server means your team’s chat history lives on your hardware, encrypted end to end, and no company can read it or change the pricing. The trade-off is that Matrix is less polished than Slack: the experience depends on which server and client you choose, and self-hosting a Matrix server is more involved than installing Mattermost.
Element is the right choice for a team that cares about data ownership above interface polish, and it is the only alternative here built on an open protocol rather than a single product.
If you already live in a bigger ecosystem
Two options deserve a mention even though they are not open source.
Microsoft Teams has a free tier that includes chat, video calls and file sharing, and it is the obvious choice if your team already uses Microsoft tools. The trade-off is the same one Slack has: the free tier has limits on search history and storage, and the paid tiers push you toward the full Microsoft subscription.
Discord is not a work tool, but it is free, has excellent voice channels, and many communities and small teams already use it. It works well for informal, community-style communication. The trade-off is that Discord is built for gaming communities, not work: it has no threads-in-the-classic-sense polish for projects, and its data lives with Discord, not you.
Both are worth knowing about, but neither is a full replacement for a team that needs work-grade search, retention and integrations.
The comparison
| Tool | Hosting | Topics/threads | Video calls | Self-hosted | Best for |
|---|---|---|---|---|---|
| Mattermost | Self-hosted or cloud | Threads | Add-on | Yes | Drop-in Slack replacement |
| Rocket.Chat | Self-hosted or cloud | Threads | Built-in | Yes | Chat plus video in one tool |
| Zulip | Self-hosted or cloud | Topics by default | Add-on | Yes | Busy teams drowning in channel noise |
| Twist | Hosted only | Threads by default | No | No | Async-first, calm communication |
| Element/Matrix | Self-hosted or federated | Threads | Built-in | Yes | Data ownership and open protocol |
| Microsoft Teams | Hosted only | Threads | Built-in | No | Teams already on Microsoft tools |
| Discord | Hosted only | Threads | Built-in | No | Communities and informal teams |
The honest bottom line
The best free alternative to Slack is the one that matches what you actually dislike about Slack.
If the problem is the bill, Mattermost is the open-source tool that replaces Slack almost one-to-one, runs on your own server, and never charges per user.
If the problem is the noise, Zulip fixes it at the root by threading every message into a topic, and Twist goes further by making the whole tool async-first.
If the problem is ownership, Element on Matrix puts your team chat on an open protocol and your data on your own server.
Two honest warnings. First, no free tool imports a Slack workspace with its full history, files and integrations intact — moving means exporting what you can and rebuilding the structure. Second, if your team already uses video calls heavily, pair your chat choice with a look at the free alternatives to Zoom, because the video side usually lives in a separate tool anyway. For the broader question of where your team’s notes and docs should live, the free alternatives to Notion cover the workspace side of the same decision.
Team chat is a solved problem, and paying for it is optional. The hard part is not the tool — it is deciding whether you want to keep the Slack model or leave it behind.
Frequently asked questions
What is the best free alternative to Slack?
It depends on what you want to change. If you want the Slack experience without the per-user bill, Mattermost is the closest open-source match and runs on your own server with no user limits. If you want a better threading model that keeps conversations organised, Zulip threads every message by topic by default. If you want async-first communication that does not interrupt your team, Twist is the fit. And if you want to own your data entirely, Element on Matrix lets you run your own server and choose any client.
Can I move my Slack history to a free alternative?
Not in one click. Slack lets you export a workspace's public channels and files, but no free tool imports that export with the full history, threads, reactions and integrations intact. The practical approach is to export for reference, rebuild your channels and topic structure in the new tool, and keep Slack available in read-only mode while your team works through the transition. Moving the people is quick; moving the history is the slow part.
Which free Slack alternative is self-hosted?
Mattermost, Rocket.Chat, Zulip and the Matrix server that powers Element can all run on your own hardware. Once installed, you control the accounts, the data and the message retention policy, with no third party that can change the pricing or read your messages. The trade-off is that you need somewhere to run the software and the discipline to keep it updated and backed up.
Why would a team leave Slack if it already works?
Most teams leave for one of three reasons. The first is cost: Slack's per-user pricing scales as the team grows, and a tool that felt cheap at ten people feels heavy at fifty. The second is message retention: the free tier limits how far back you can search, and teams that rely on that history hit the limit quickly. The third is noise: a busy Slack becomes a stream of messages you feel obliged to read, and tools like Zulip and Twist exist precisely because that model does not scale for everyone.
Is a self-hosted chat server safe?
It is as safe as the machine it runs on and the person who maintains it. A self-hosted Mattermost or Matrix server keeps your data on your own hardware, which means no vendor can read it or change the terms. But it also means updates, backups and security are your responsibility. A self-hosted server that goes unpatched for months is a risk, not a safety feature. If you are not comfortable maintaining a small server, a hosted free tier is the safer practical choice.
