What is the best free Slack alternative?

For a group of up to 25 people, Probed is free with the whole message history kept. Discord is free at any size. Zulip, Mattermost and Element are free if you host them yourself. Slack's own free plan only shows the last 90 days of messages.

Is there a Slack alternative that doesn't charge per user?

Yes. Probed charges one price per space: free up to 25 members, then $19 a month for up to 250, and members never pay. Discord is free for everyone in a server. Most work chat tools, including Slack, Teams and Google Chat, are priced per person.

Can I use a Slack alternative and keep my team on Slack?

With Probed, yes. On paid plans it keeps channels in sync with Slack in both directions, so your team can stay in Slack while your community or customers talk in Probed.

The best Slack alternatives for communities and small teams

We make Probed, so weigh this list with that in mind. We’ve tried to say plainly where each option is better than ours.

Start with who’s in the conversation

Slack is built for coworkers. Most people looking for an alternative have hit one of these:

The bill grows with every person, and you’re inviting people who aren’t employees.
History is hidden after 90 days on the free plan, and deleted after a year.
It’s a community, not a company, and Slack’s workspace model feels like an office.
You want to own the software and run it yourself.
You already pay for Microsoft 365 or Google Workspace and want chat included.

The options

Probed

A chat app with channels, threads, DMs and voice rooms with video and screen share, plus events, an ideas board where members vote and a public roadmap. One plan per space, members never pay, and every message is kept on every plan, free included. On paid plans it keeps channels in sync with Slack or Discord, so you can move gradually or run both.

Best for: communities, creators and small companies talking with their customers, or anyone tired of paying per seat for people who aren’t employees.
Trade-offs: free up to 25 members, then $19 a month for up to 250. Far fewer integrations than Slack, lighter admin and compliance controls, and no Android app yet (it works in the browser there).

Discord

Free chat and voice at any size, with a huge bot ecosystem.

Best for: large or casual communities that need to stay free.
Trade-offs: it feels like a gaming platform to many groups, members are nudged toward Nitro, and good ideas scroll away in busy channels. See the best Discord alternatives if that’s the problem.

Microsoft Teams

Chat, meetings and files, included with many Microsoft 365 plans.

Best for: companies already on Microsoft 365.
Trade-offs: priced per person, heavy for a community, and outsiders join as guests with limits.

Google Chat

Chat built into Google Workspace, next to Gmail, Meet and Drive.

Best for: small teams already living in Google Workspace.
Trade-offs: fewer community features than Slack, and the full version needs Workspace, priced per person (personal Google accounts get a basic free version).

Mattermost

Open-source team chat you can host yourself, with a strong focus on security and compliance.

Best for: technical teams and organisations that must keep data on their own servers.
Trade-offs: self-hosting means running and upgrading it yourself, and paid plans are priced per user.

Zulip

Open-source chat organised by topics, which keeps busy conversations readable.

Best for: large, technical or async teams and open-source projects.
Trade-offs: the topic model takes getting used to, and it’s less of a hangout.

Element

A chat app on the open Matrix protocol, with end-to-end encryption.

Best for: privacy-minded groups and organisations that want an open, federated network.
Trade-offs: rooms and federation can confuse people coming from Slack.

Moving over without losing people

Don’t switch overnight. Start the new space with the people who talk most, move announcements first, and keep the old workspace open for a while. On paid plans, Probed keeps channels in sync with Slack in both directions while people move. See the full Probed vs Slack comparison, and what happens to old messages on Slack’s free plan.