Slack vs Discord vs Mattermost for a 10-person team (2026)

Zero dollars a year is a real option here, twice over — Discord is free, and Mattermost is free if you're willing to host it yourself. Slack is the one paid option in this comparison, at roughly $7.25–$12.50/user/month depending on plan and billing, and for a ten-person team that's real money: somewhere between $870 and $1,500 a year for something two competitors give away.

| Tool | Free tier | Paid | 10 users/year |
|---|---|---|---|
| Discord | full features; Nitro ($9.99/mo) is optional and per-person | — | $0 (or Nitro à la carte) |
| Mattermost | self-hosted, unlimited | Professional — ~$10/user/mo (cloud) | $0 self-hosted / ~$1,200 cloud |
| Slack | 90-day history, limited integrations | Pro — ~$7.25–$12.50/user/mo | ~$870–$1,500 |

So why does anyone pay? Slack's free tier caps message history at 90 days — everything older simply becomes unsearchable, which is the single biggest reason teams end up upgrading, not any particular feature they were missing. What Pro actually buys is unlimited history, real compliance tooling, and by far the most mature third-party app directory of the three, plus Slack Connect for talking to people outside your own organization without adding them as guests.

Discord doesn't compete on any of that — it competes on being free, having genuinely excellent voice and screen-share, and feeling less like enterprise software, which is exactly why community-driven and informal teams gravitate toward it. What it's weak on is precisely what Slack is strong on: threading that holds up in a busy channel, compliance, and the kind of business-tool integrations a company with a sales team or a support queue actually needs.

Mattermost is the odd one out by design — open source, Slack-like in almost every visible way, and free in the way that matters most if security or regulatory requirements mean chat data has to live on infrastructure you control rather than a vendor's servers. That's a narrow but real need, and for the teams that have it, nothing else on this list is really a substitute.

A small team on a tight budget does fine on free Slack (just accept the 90-day limit as a real constraint, not a footnote) or Discord if voice is part of daily work. A growing company that keeps hitting that history wall should just pay for Slack Pro — it's not close for anyone doing real business communication. And a regulated or security-conscious org should be looking at self-hosted Mattermost before either of the other two, because the constraint driving that choice isn't really about price at all.