How to Switch from Slack to Mattermost: A Complete Guide
Slack — owned by Salesforce — is ubiquitous in tech-forward workplaces, but its US ownership, data stored in US infrastructure, and rising prices have pushed many Canadian organizations to explore alternatives. Mattermost is an open-source team messaging platform that you can self-host on Canadian servers, giving you complete control over your data and communications. For security-conscious organizations, regulated industries, and government teams, self-hosted Mattermost is the gold standard for communication sovereignty.
What You'll Gain
- Full data sovereignty: Self-hosted on your own Canadian servers or a Canadian cloud provider. Your messages, files, and channels never leave Canadian infrastructure.
- Open source: Mattermost's source code is auditable — no black-box data collection, no surprise feature changes, no pricing hikes. You can verify exactly what the software does.
- Cost control: At scale, self-hosted Mattermost dramatically reduces per-seat costs compared to Slack's $12.50+/user/month pricing. Infrastructure costs are the main variable.
- Customizability: Build custom integrations, slash commands, and bots that Slack's API doesn't support. Mattermost's open architecture enables deep workflow automation.
- Compliance features: Enterprise Mattermost includes compliance exports, eDiscovery support, and audit logging — critical for legal, government, and regulated industries.
What You Might Miss
- IT overhead: Self-hosting means you're responsible for server maintenance, backups, updates, and availability. Cloud-hosted Mattermost options exist but add cost.
- Smaller app ecosystem: Slack's app directory has 2,400+ integrations. Mattermost supports many of the same integrations but requires more setup.
- Migration complexity: Moving years of Slack message history and channel structure is a real project. Budget time for the migration and change management.
- User adoption: Mattermost looks similar to Slack but isn't identical. Expect 1–2 weeks of adjustment as your team re-learns keyboard shortcuts and interface patterns.
What You'll Need
- Admin access to your current Slack account for data export
- Mattermost account (trial available)
- 2–4 hours for initial setup and configuration
- A test group of 5–10 users for the pilot phase
- A communication plan for your team about the transition
Step-by-Step Migration
- Export Slack data: Use Slack's workspace export (Admin → Settings → Export) to export all message history. For Slack Pro/Business+, export all channels. For Free, only public channels export.
- Choose your hosting: Decide between self-hosted (on your own servers or a Canadian cloud like OpenStack at Fido/Rogers), Mattermost Cloud, or a managed Mattermost provider. For maximum sovereignty, self-host on Canadian infrastructure.
- Install and configure Mattermost: Deploy Mattermost server. Configure authentication (LDAP/SAML if using SSO), set up email notifications, and configure file storage on Canadian infrastructure.
- Import Slack data: Mattermost includes a Slack import tool. Import your channel structure and message history. Note: Slack Free exports have limitations; paid exports are more complete.
- Recreate channels and permissions: Review imported channels. Set up private channels, guest access, and team permissions to match your Slack structure.
- Configure integrations: Reconnect your key Slack integrations: GitHub notifications, Jira, calendar bots, etc. Most have Mattermost equivalents or webhooks.
- Run parallel for two weeks: Keep Slack active while the team onboards to Mattermost. Gradually migrate active channels and workflows before archiving Slack.
Tips for the Transition
- Use Mattermost's bulk import tool for large Slack workspaces — the web interface import is limited to smaller exports.
- Configure Mattermost's mobile apps before announcing the switch — mobile experience is important for adoption.
- Set up a #mattermost-tips channel with Slack-to-Mattermost keyboard shortcut translations for your first two weeks.
- Consider Mattermost's "Data Retention" policy to manage message history storage costs on your own infrastructure.
The Canadian Angle
Self-hosting Mattermost on Canadian infrastructure (AWS Canada Central, OVHcloud Beauharnois, or your own colo) puts your team communications under Canadian legal jurisdiction. For government agencies, healthcare teams, and legal professionals, this is the highest level of communication data sovereignty available.
Timeline
Plan 3–6 weeks for a full Mattermost migration: 1 week for infrastructure setup, 1 week for import and configuration, 2–4 weeks for parallel running and change management.