Slack vs Mattermost: Team Chat Compared (2026)
Slack and Mattermost are both channel-based team chat platforms, built for different organisations.
- Verified 27 Oct 2026Sources are dated on this page
- 7 sourcesLinked, typed and dated
- No winner declaredFit depends on your criteria
- Not tested by Stack18Editorial summary of documented facts
Slack vs Mattermost: the short answer
Slack and Mattermost are both channel-based team chat platforms, built for different organisations. Slack is a cloud messaging platform from Salesforce, sold per user in Free, Pro, Business+ and Enterprise+ plans. Mattermost is an open-source, self-hostable platform aimed at security-conscious and regulated teams, sold through prepaid annual subscriptions on Professional, Enterprise and Enterprise Advanced plans, with an open-source edition.
The sources reviewed describe the choice as convenience against control. Slack is described as the more polished product with a far larger app directory and bundled AI. Mattermost is described as the stronger option when data must stay on your own infrastructure, including air-gapped and disconnected environments, and for engineering and incident-response workflows, at the cost of setup and a smaller ecosystem.
We compare what independent 2026 sources and Slack's own comparison page support and mark the rest Unknown. Mattermost's plans are quote-based on its site, so its prices come from third-party listings. Slack's page is vendor-authored. No winner is declared: the better fit depends on where your data must live.
Choose Slack if you- Teams that want a polished hosted chat tool with a large app directory
- Teams that collaborate with outside partners through Slack Connect
- Organisations without the capacity to run their own infrastructure
Choose Mattermost if you- Regulated or security-conscious organisations that must control where data lives
- Engineering and operations teams that run incident response from chat
- Organisations that want private AI agents inside their own environment
Slack and Mattermost at a glance.
One card per product, drawn from each full profile. Open a profile for features, pricing plans, limits and sources.
Slack
Slack Technologies (Salesforce) · Collaboration Software
Slack is a team messaging and collaboration platform, owned by Salesforce, that organises conversations into channels and offers huddles, search, integrations and AI features, sold per user in Free, Pro, Business+ and Enterprise+ plans.
- Pricing
- Free plan; Pro reported at $7.25 per user per month billed annually.
- Best for
- Teams that want real-time channel-based communication
Mattermost
Mattermost, Inc. · Collaboration Software
Mattermost is a collaboration platform for channel-based messaging, calls, playbooks, boards and AI agents that organisations can run self-hosted, in a private cloud or in air-gapped environments. It is licensed as prepaid annual seat subscriptions on Professional, Enterprise and Enterprise Advanced plans.
- Pricing
- Plans are quote-based on Mattermost's site; third-party listings report Professional from about $10 per user per month billed annually. A free limited-use edition is offered for technical evaluation.
- Best for
- Regulated or security-conscious organisations that need to control where data lives
Slack vs Mattermost: feature-by-feature comparison.
Every row is drawn from the sources listed below. Rows that differ are marked, and you can filter the table to show only those.
- YesDocumented
- PartialAvailable with limits or on some plans
- NoDocumented as unavailable
- UnknownNot documented in the sources reviewed
| Dimension |  Slack |  Mattermost |
|---|---|---|
| Product | ||
| Core approach | YesCloud-hosted channel messaging with huddles, canvases, workflows and a large app directory. | YesOpen-source, self-hostable messaging and collaboration platform for secure and regulated teams. |
| Hosting | ||
| Deployment model | YesCloud-hosted by Slack. | YesSelf-hosted, private cloud or managed cloud, including air-gapped environments on Enterprise Advanced. |
| Pricing | ||
| Free optionDiffers | YesFree plan with 90-day message history and limited integrations. | PartialA free open-source self-hosted edition and a limited-use evaluation edition; a permanent hosted free tier was not confirmed. |
| Paid price per user (annual)Differs | YesPro at $7.25 and Business+ at $15 per user per month; Business+ rose from $12.50 in 2025. | PartialProfessional is quote-based; third-party listings report about $10 per user per month billed annually. |
| Enterprise | PartialEnterprise+ is custom priced. | PartialEnterprise and Enterprise Advanced are quote-based, with prepaid annual subscriptions. |
| Control | ||
| Data controlDiffers | PartialData held in Slack's cloud, with Enterprise Key Management on Enterprise+. | YesSelf-hosting gives full data control; you manage your own infrastructure. |
| AI | ||
| AI and agents | YesSlack AI bundled into paid plans, with Agentforce agents sold as paid add-ons. | YesAgents with AI search and call transcription, with the option to connect your own LLM so data stays in your deployment, per Slack's page. |
| Ecosystem | ||
| App directoryDiffers | YesGuides report 2,600+ integrations. | PartialAPI-driven with a curated plugin marketplace; described as a smaller ecosystem. |
| Engineering | ||
| Developer and incident workflowsDiffers | PartialWorkflow builder and integrations. | YesPlaybooks and incident-response workflows described as a strength. |
| Compliance | ||
| Compliance claims | PartialSlack's page lists SOC 2, HIPAA and FedRAMP. | PartialSlack's page lists ISO 27001, HIPAA and FINRA for Mattermost; confirm with Mattermost. |
| Ease of use | ||
| Setup effortDiffers | YesDescribed as adopted in a day, with a polished interface. | PartialSelf-hosting requires setup and infrastructure that must grow with headcount; described as less polished. |
| External | ||
| Working with outside partnersDiffers | YesSlack Connect for messaging with external organisations. | PartialFederated communications on Enterprise; details were not itemised. |
Slack vs Mattermost pricing.
Slack pricing
Per user per month by plan, with discounts for annual billing. Enterprise+ is custom-priced.
- Free$0
- Pro$7.25 per user per month billed annually; $8.75 billed monthly
- Business+$15 per user per month billed annually; $18 billed monthly
- Enterprise+Custom
Figures reported consistently by independent sources; vendor page not reviewed directly. Checked 15 Oct 2026.
All Slack plans and sources
Mattermost pricing
Prepaid annual subscriptions by seat on Professional, Enterprise and Enterprise Advanced plans. Prices are quote-based on the vendor's site.
- Free evaluation edition$0
- ProfessionalContact sales; third-party listings report about $10 per user per month billed annually
- EnterpriseQuote on request
- Enterprise AdvancedQuote on request
Structure only; figures not recorded. Checked 20 Oct 2026.
All Mattermost plans and sourcesSlack is the cheaper way to buy a hosted product, and Mattermost's cost depends on who runs the servers. Our arithmetic on reported annual prices for 100 users gives about $8,700 a year on Slack Pro ($7.25 x 100 x 12) and $18,000 on Business+ ($15 x 100 x 12), against about $12,000 on Mattermost Professional at the reported $10 ($10 x 100 x 12). Mattermost's price is a third-party figure, since Mattermost quotes plans on request.
Self-hosting adds costs that list prices do not show: servers, administration, backups and high availability, which Mattermost's Enterprise tier is described as covering. One source contends self-hosted chat can cost a small fraction of Slack for 100 users, but it comes from a managed-hosting vendor and leaves out staff time, so treat it with caution.
Slack's Business+ rose 20 percent in 2025 and bundled AI, with Agentforce agents sold separately. Confirm current terms with both vendors.
Prices and plans change. Confirm current terms with each vendor before you decide.
Slack vs Mattermost: implementation, ecosystem, AI and security.
Ease of implementation and usability
We did not test setup or migration for either product. Slack is a cloud app that teams adopt in a day, while Mattermost needs deployment planning for self-hosted or private-cloud installs, though managed cloud is also offered. Pilot with one team and your real compliance requirements.
Integrations and ecosystem
Guides report Slack has 2,600+ integrations. Mattermost is described as API-driven with a curated plugin marketplace and strong DevOps connections. Check the specific tools you use.
AI capabilities
Slack AI offers summaries, search and recaps on paid plans, with Agentforce agents as add-ons. Mattermost offers agents with AI search and call transcription, and lets you connect your own LLM so data stays inside your deployment. We did not test output quality for either product.
Security, deployment and administration
Slack's page lists SOC 2, HIPAA and FedRAMP, with Enterprise Key Management on Enterprise+. Mattermost's higher plans add federated communications, compliance and zero-trust controls, and Enterprise Advanced adds air-gapped support. We did not verify certifications for either, so request current security documentation.
Slack and Mattermost: each option, in balance.
Slack
Strengths and limitations from the profile
- A free plan lets small teams start without paying, with Slack Connect for external messaging.
- AI is bundled into paid tiers instead of sold as a separate add-on, with advanced AI on Business+.
- Unlimited integrations on Pro and Business+ let teams connect many tools.
- Business+ adds compliance exports and a 99.99 percent uptime SLA for organisations with governance needs.
- Per-user pricing grows quickly with team size, and external guests can add to cost.
- The Free plan limits message history to 90 days and integrations to 10.
- Advanced AI needs Business+, so teams on Pro get only basic AI features.
- Many connected apps charge separately, which raises total cost.
Mattermost
Strengths and limitations from the profile
- It can run self-hosted, in a private cloud, on sovereign cloud or fully air-gapped, so data stays under the customer's control.
- Bring-your-own and multi-LLM agent support, an MCP connector and admin tool policies let teams run AI in their own environment.
- Retention policies, legal hold, eDiscovery exports and delegated administration address compliance needs.
- Playbooks, boards and connectors for tools such as Jira, GitHub and GitLab bring operational workflows into chat.
- Pricing is quote-based, so costs cannot be calculated from the vendor's public pages.
- Self-hosting means the customer takes on infrastructure, patching, backups and maintenance.
- Workflow automation, work management, compliance tools and high-scale options are Enterprise features rather than Professional.
- Each server needs its own licence, including non-production servers.
Slack or Mattermost: which fits which situation?
No overall winner is declared. The better choice depends on the criteria that matter most to you, so test both against your own requirements.
Choose Slack if you…
- Teams that want a polished hosted chat tool with a large app directory
- Teams that collaborate with outside partners through Slack Connect
- Organisations without the capacity to run their own infrastructure
Choose Mattermost if you…
- Regulated or security-conscious organisations that must control where data lives
- Engineering and operations teams that run incident response from chat
- Organisations that want private AI agents inside their own environment
Switching between Slack and Mattermost.
Moving between Slack and Mattermost means migrating channels, history and files, rebuilding integrations and workflows, and retraining habits. Self-hosting adds a deployment project. Run both in parallel for one team and set a firm cut-off date.
- Export a sample of your data and test an import into the other product.
- List the automations, integrations and permissions you would need to rebuild.
- Pilot with one team before a full cut-over.
- Check contract terms and notice periods with both vendors.
General guidance, not specific to either vendor. Confirm migration options with the vendors.
Slack vs Mattermost: questions and answers
Is Mattermost free?
Mattermost has an open-source self-hosted edition and a limited-use evaluation edition, but running it costs infrastructure and administration. A permanent hosted free tier was not confirmed.
Is Slack or Mattermost cheaper?
Slack Pro at $7.25 per user per month is cheaper than Mattermost Professional at about $10 (third-party figure), billed annually. Mattermost's open-source edition has no licence fee.
Can I self-host Slack?
No. Slack is cloud-hosted. Mattermost can be self-hosted, run in a private cloud or used as managed cloud.
Which has better AI?
Slack bundles AI into paid plans, and Mattermost lets you connect your own LLM inside your deployment. The sources reviewed do not support a quality ranking.
Which has more integrations?
Guides report Slack has 2,600+, and Mattermost has a curated plugin marketplace and open APIs.
Can Mattermost run in an air-gapped environment?
Mattermost lists air-gapped and disconnected-environment support on Enterprise Advanced.
Which is better for engineering teams?
Guides describe Mattermost as strong for engineering and incident response, with playbooks, and Slack as strong for broad team messaging.
Where this comparison comes from.
- Pricing Mattermost Official Accessed 20 Oct 2026
- Slack vs. Mattermost (published by Slack) Slack Official Accessed 27 Oct 2026
- Slack vs. Mattermost: Which Collaboration Tool Is Best? (ClickUp sells a competing product) ClickUp Third-party Accessed 27 Oct 2026
- Mattermost vs Slack (Pumble sells a competing chat tool) Pumble Third-party Accessed 27 Oct 2026
- Slack alternatives in 2026 Carly Third-party Accessed 27 Oct 2026
- Slack vs. Microsoft Teams Zapier Third-party Accessed 27 Oct 2026
- Slack vs Teams: Which is Better for Your Business in 2026? CloudFuze Third-party Accessed 27 Oct 2026
Comparison rows summarise the sources listed and the two profiles. Confirm current details with each vendor. Stack18 has not tested either product. One or both profiles are secondary-source profiles: vendor pages were not reviewed directly, so verify figures with the vendors.
Ready to test Slack and Mattermost?
Check each vendor's current pricing and terms, run both against a real scenario from your business, or talk to Stack18 if off-the-shelf software is not the answer.
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