Mattermost

Mattermost is an open source messaging platform with 31k+ GitHub stars — a Slack alternative with full data control and compliance features.

Compare Mattermost with Microsoft Teams and Discord before you choose your stack.

Key features

Messaging

• Channels, DMs, and group messages
• File sharing with previews
• Threads and mentions
• Markdown formatting

Integrations

• Webhooks, bots, slash commands
• Jira, GitHub, GitLab integrations
• Playbooks for incident response
• Custom app framework

Compliance

• Data retention policies
• eDiscovery and legal hold
• Audit logging
• HIPAA and FedRAMP ready

Mattermost vs Slack

	Mattermost	Slack
License	MIT (open source)	Proprietary
Deployment	Self-hosted available	Cloud SaaS
Data control	Your infrastructure	Vendor infrastructure
Customization	Full source access	Limited to vendor features
Cost	Free open-source software	Subscription or usage fees

Choose Mattermost if you want open-source code, self-hosting options, and full control over your data and deployment.

Choose Slack if you prefer a managed proprietary product with vendor support and minimal setup.

Browse more open-source alternatives to Slack, or explore other tools in Communication & Community.

At a glance

License	MIT (core)
Stack	Go, React
Self-hosted	Yes
Cloud	mattermost.com
Database	PostgreSQL

Self-hosting

docker run -d --name mattermost -p 8065:8065 mattermost/mattermost

Includes desktop and mobile apps.

Why OSSBase Recommends Mattermost

Mattermost is one of the few mature self-hosted collaboration platforms capable of replacing Slack in regulated environments. Unlike most proprietary chat tools, it can be deployed entirely on your own infrastructure while still offering enterprise-grade compliance features, workflow automation, and integrations.

Our Deployment Verdict

Deployment tested

Aspect	Details
Method	Docker Compose or binary install
Time	≈30 minutes to first running instance
Required services	PostgreSQL 14+, SMTP, reverse proxy (NGINX)
Difficulty	Intermediate — configuration required, but well-documented

Hidden cost: SMTP is not optional for production. Notifications, password resets, and email integrations all fail silently without it. Budget time for SMTP configuration and testing.

Our assessment: Mattermost is genuinely enterprise-grade because compliance features actually work—not bolted on. HIPAA and FedRAMP certifications mean real deployments in regulated industries. Teams running it include hospitals and government agencies, not just tech startups.

The catch: it assumes a dedicated DevOps person exists on staff. A 200-person team with one part-time sysadmin should think twice.

OSSBase Recommendation

Choose Mattermost if:

• Your organization requires compliance certifications (HIPAA, FedRAMP, SOC 2)
• Your team has dedicated infrastructure staff
• Open-source code auditing matters more than vendor SLAs

Skip Mattermost if:

• You want a zero-maintenance team chat tool
• Your entire company is under 20 people
• You don't have DevOps resources to spare

Sources

• Hardware requirements
• Docker deployment guide
• Pricing & editions