Slack vs Mattermost
Slack is the most popular team messaging platform with a rich ecosystem and cloud-hosted convenience. Mattermost is an open-source, self-hostable Slack alternative popular with organizations that need data sovereignty, air-gapped deployments, or compliance requirements that cloud SaaS cannot meet. Slack wins on ease; Mattermost wins on control.
Build your own internal tools freeSide-by-side
Where work happens vs The open-source messaging platform that enables DevSecOps teams.
| Feature | Slack | Mattermost |
|---|---|---|
| Pricing from | Free–$12.50/user/mo | Free (OSS)–$10/user/mo |
| Pricing | Free; Pro $7.25/user/mo; Business+ $12.50/user/mo | OSS free (self-hosted); Professional $10/user/mo cloud |
| Best for | Teams wanting best-in-class cloud messaging | Teams needing on-prem or air-gapped deployment |
| Self-hosting | Not available | Yes, full self-hosted deployment |
| Open-source | No | Yes, MIT licensed |
| Security certifications | SOC 2, ISO 27001, HIPAA | FedRAMP High, DISA IL4, HIPAA |
| Integrations | 2,400+ integrations | 700+ integrations via plugins |
Slack or Mattermost? Who each tool is best for
Slack
Where work happens
- Pricing: Free; Pro $7.25/user/mo; Business+ $12.50/user/mo
- Best for: Teams wanting best-in-class cloud messaging
- Self-hosting: Not available
- Open-source: No
Starting from Free–$12.50/user/mo
Mattermost
The open-source messaging platform that enables DevSecOps teams
- Pricing: OSS free (self-hosted); Professional $10/user/mo cloud
- Best for: Teams needing on-prem or air-gapped deployment
- Self-hosting: Yes, full self-hosted deployment
- Open-source: Yes, MIT licensed
Starting from Free (OSS)–$10/user/mo
How Appaca works
Appaca is not another SaaS tool to evaluate. It builds you a working app from a plain description — with database, dashboards, and team access — and runs it on the platform.
Describe what you need
Tell Appaca what you need in plain language. No forms, no setup wizard — just describe the job to be done.
Chat with AI to refine it
Appaca AI builds your app and stays available to refine it. Change behaviour, add fields, adjust flows — all in chat.
Use it immediately
Your app runs on Appaca with a built-in database, file storage, and team access. No deployment, no devops.
Everything your team needs, built in
Appaca provides the full stack for internal and personal software — no integrations to wire up, no hosting to manage.
Build and update apps by chatting with AI
Describe what you need and Appaca builds a working app. Come back any time to refine it — add new fields, change behaviour, or extend functionality — all without writing code.
Built-in database and file storage
Every Appaca app comes with a secure database and file storage ready to use. No external service to connect, no schema to design — Appaca handles the data layer automatically.
Connect to services your team already uses
Appaca apps can connect to Google Sheets, Slack, Airtable, and any service that supports an API or webhook — so your app fits into your existing workflow instead of replacing it.
Building software for how your team actually works?
While you're comparing Slack and Mattermost, you might have other tools your team actually builds and maintains — trackers, dashboards, internal workflows. Appaca builds those from a plain description, with a database and team access included. No code, no devops.
- Describe what you need, get a working app in minutes
- Built-in database, dashboards, and team access
- Iterate with chat — no engineer needed
- Free to start, no per-seat pricing
Common questions
For core messaging, channels, and search, Mattermost is comparable. Slack's advantage is in its app ecosystem and user experience polish. Mattermost is most valuable for its self-hosting and compliance certifications.
Yes, Mattermost has FedRAMP High authorization, making it suitable for US federal agencies and defense contractors with the strictest data classification requirements.
Mattermost can be deployed in air-gapped environments without internet connectivity, which is critical for defense and intelligence organizations. Messages are stored on your own servers with no data ever leaving the network perimeter.
Appaca is a platform for personal software. You describe what you need and Appaca builds a working app with a database, dashboards, and team access — no code or deployment required. It is not a replacement for the tools compared on this page. Try it free at appaca.ai.