The established competitors worth comparing against Slack — researched and reviewed by our editorial team.
Discord
Best for: Communities, small teams, and gaming-adjacent groups who want free and feature-rich
Discord started in gaming and quietly became the default community platform for everyone else — open-source projects, creator audiences, study groups, and small startup teams. The chat itself is full-featured for free, with voice / video / screen-share built in. The case for using it as your team chat: it's free forever and the feature ceiling is high.
Free, $9.99/mo Nitro (cosmetic perks), $5/mo Nitro Basic
Pros
- ✓Free forever, no message history limits
- ✓Voice channels, screen share, and video built in — no Zoom needed
- ✓Massive user base means everyone already has an account
- ✓Bots and automations richer than Slack's app directory
Cons
- ×Gaming-shaped defaults can feel unprofessional for client-facing teams
- ×Threading and channel organization weaker than Slack
- ×Admin controls less mature for business use
- ×No SCIM / SSO for enterprise identity providers
Microsoft Teams
Best for: Companies already paying for Microsoft 365 — Teams comes "free" inside the bundle
Teams is the default if your organization runs on Outlook, Excel, and SharePoint. The integration with the Office suite is genuinely deep — calendar, mail, and document collaboration all flow through it. The chat experience is functional but historically clunkier than Slack; recent versions have closed the gap meaningfully.
$4/user/mo Essentials, included with Microsoft 365 ($6-22/user/mo)
Pros
- ✓Bundled with M365 — effectively free for any org already on it
- ✓Calendar, mail, file collaboration all tightly integrated
- ✓Enterprise-grade admin, compliance, and identity controls
- ✓Strong video conferencing built in
Cons
- ×Heavy, multi-window experience — slower than Slack on cold start
- ×Channels-vs-teams hierarchy confuses new users for weeks
- ×External collaboration friction (federated chat is improving but still spotty)
- ×Tied to the Microsoft ecosystem — bad fit if your stack is Google
Mattermost
Open sourceSelf-hostBest for: Compliance-heavy, dev-heavy teams who want a self-hosted Slack
Mattermost is the most Slack-like of the open-source chat options, with self-hosting, on-premise deployment, and a feature set built around developer workflows (built-in incident response, ChatOps, deep integrations with Jira, GitHub, Jenkins). Defense, fintech, and healthcare teams use it for data residency reasons.
Free Self-Hosted, $10/user/mo Cloud Pro, $15/user/mo Enterprise
Pros
- ✓Self-hostable — your data stays in your infrastructure
- ✓Open source (MIT license) with a healthy paid tier for support
- ✓Built-in incident management and ChatOps workflows
- ✓Strong compliance posture (FedRAMP, ITAR, HIPAA)
Cons
- ×You're running infrastructure if you self-host (or paying cloud rates that approach Slack's)
- ×UI less polished than Slack
- ×Smaller app/integration ecosystem
Rocket.Chat
Open sourceSelf-hostBest for: Teams who want self-hosted chat with omnichannel customer-support baked in
Rocket.Chat is the other major open-source Slack alternative, with a slightly different focus: omnichannel customer engagement. It bundles internal team chat with customer messaging across WhatsApp, SMS, and live-chat widgets. If you need both, that's a real reason to look at it over Mattermost.
Free Community, $4/user/mo Pro, custom Enterprise
Pros
- ✓Self-hostable + open source
- ✓Omnichannel customer chat (WhatsApp, SMS, web widget) included
- ✓Federation between Rocket.Chat instances — chat across orgs
- ✓Strong for support-oriented teams
Cons
- ×Free community tier limited compared to paid plans
- ×Setup and maintenance overhead if self-hosted
- ×UI feels older than Slack and Mattermost
Twist
Best for: Remote, async-first teams that want chat to look more like email and less like a casino
Twist is built by the team behind Todoist on a single contrarian premise: real-time chat is bad for deep work. Conversations are organized as threads, you're not pressured to reply instantly, and notifications are deliberately quiet. The bet is that async-first defaults compound into a calmer, more productive team.
Free, $6/user/mo Unlimited
Pros
- ✓Async-first defaults — no green dots, no read receipts, no urgency theater
- ✓Thread-as-document model better for distributed teams and time zones
- ✓Cleaner search than Slack — every thread is a permanent record
- ✓Reasonable pricing
Cons
- ×Slower to react to genuine emergencies
- ×Smaller integration ecosystem than Slack
- ×Real-time chatters will resist the cultural shift
