Step-by-step: migrating your team from Slack to a self-hosted Matrix setup

I recently led a migration of a mid-sized engineering team from Slack to a self-hosted Matrix setup, and I want to share the step-by-step playbook I used. If you’re contemplating the same move, you likely want more control over data, better federation options, or cost predictability. That’s exactly why we moved. In this guide I’ll cover planning, architecture choices, data migration strategies, day‑to‑day operations, and the user-facing parts that make or break adoption.

Why self-hosted Matrix — quick reality check

Matrix gives you an open standard for real‑time communication, end‑to‑end encryption (E2EE), and the flexibility of federation. Self‑hosting preserves control over metadata and files and reduces vendor lock‑in. But it’s not a drop‑in replacement for Slack: features like message search, advanced integrations, and polished UI behaviors can differ. If your team values privacy, cross‑server federation, or running everything on your own infrastructure, Matrix is a solid choice.

High‑level migration plan I used

• Assess current Slack usage and critical integrations
• Choose Matrix server (homeserver) implementation and hosting
• Set up core infrastructure: homeserver, database, media repo, reverse proxy, TLS
• Plan account provisioning and identity mapping
• Migrate chat history and files selectively
• Set up bridges and bots for legacy tooling
• Roll out pilots, train users, and iterate

Assess Slack usage — what to audit first

Before you touch any infra, understand how Slack is used. I audited:

• Active channels and private groups vs. archived ones
• Direct messages volume
• Integrations: CI, monitoring, calendars, SSO, bots
• File storage: how many files and average sizes
• Compliance needs: retention, export requirements

This determined what to import and which integrations must be rebuilt or bridged. For example, we kept a small set of audit channels archived in Slack export but migrated active channels and files to Matrix.

Choose your homeserver implementation

Options include Synapse (widely used, mature), Dendrite (lighter, in development), and Conduit (fast, Rust‑based). I chose Synapse for its stability, ecosystem, and admin tools.

Hosting choices:

• Self‑managed on VMs or bare metal
• Containerized (Docker Compose) for small teams
• Kubernetes for larger setups with autoscaling
• Managed hosting providers if you want less ops

We ran Synapse on a small Kubernetes cluster and used PostgreSQL for the database and an object storage (MinIO backed by S3) for media to keep files scalable and cheap.

Essential infrastructure components

• Synapse homeserver (or your chosen server)
• PostgreSQL for performance and reliability
• Media repository (local disk or S3/MinIO)
• Reverse proxy (Nginx) with TLS
• Identity provider or SSO (SAML/OIDC) if you use SSO
• Redis for caching (optional but useful)
• Backups: DB snapshots and media archive

Example architecture decisions I made

Account provisioning and identity mapping

Mapping Slack users to Matrix accounts can be manual or automated. If you have SSO (SAML/Okta), integrate Synapse with your IdP — this gives the smoothest UX. For our team, we enabled SSO and also created fallback email/password accounts for contractors.

• Provision accounts prior to migration to reduce friction
• Send invites with clear onboarding steps
• Keep Slack open in read‑only for a transition period

Message and file migration strategies

There’s no perfect, one‑click Slack->Matrix migration. I considered three approaches:

• Export Slack data and import into Matrix rooms (best for channels you truly need)
• Bridge Slack to Matrix so history remains accessible via Slack bridge
• Leave historical data in Slack and provide links from Matrix

We selectively imported active channels using Slack's export tool and a community script that converts Slack JSON to events compatible with the Matrix room state. For files, we reuploaded to the Matrix media repo and rewrote message attachments to point to the new media URLs.

Using bridges

For integrations and a safe transition, set up bridges:

• matrix-appservice-slack — this allows Matrix rooms to mirror Slack channels while you migrate people over time
• Bridges for IRC, XMPP, and GitHub are also available if you need them

Bridges introduce complexity: they need stable network access, and you should secure tokens. We used a bridge during the 4‑week migration window and then decommissioned it channel by channel.

Encryption and key management

End‑to‑end encryption is available via Olm/Megolm. It’s powerful but complicates migration: you can’t import plaintext messages into an encrypted room without the encryption keys recorded at the time. Consider these tradeoffs:

• For private channels requiring E2EE, plan for fresh rooms and accept that historical messages will be archived outside E2EE.
• Use server‑side encryption for stored backups and secure the backups' encryption keys.

User training and change management

Communication is everything. I ran live demos, created short how‑tos, and maintained a "Matrix FAQ" channel during rollout. Key topics:

• Client recommendations: Element for desktop/web, ElementX for advanced users
• How to manage notifications and mention behavior differences
• How to search messages (Matrix search is improving; show practical tips)
• How to use threads (Matrix threading differs from Slack — we taught people to use relays and explicit thread replies)

We also held open office hours for two weeks to help people with account issues and to refine room structures based on real usage.

Operations and maintenance

Set up monitoring (Prometheus + Grafana works well with Synapse metrics), automated backups, and an incident runbook. I recommend:

• Daily DB and media backups with offsite copies
• Alerting for high CPU, memory, database connection issues, and media storage capacity
• Periodic policy reviews for retention and access controls

Things I wish I’d known earlier

• Plan for search limitations — we augmented with full‑text DB indices and third‑party search when needed
• Bridge tokens and API keys are sensitive — rotate and store securely
• Expect some users to resist change; small pilot teams help create internal champions
• Test media size limits and tune upload limits to avoid rejected attachments

Quick checklist before you flip the switch

• Homeserver healthy and tested end‑to‑end
• SSO integration tested with a staging group
• Bridges running for critical integrations
• Message and file migration for priority channels completed
• User onboarding materials and office hours scheduled
• Backups and monitoring configured

Migrating from Slack to a self‑hosted Matrix setup is an investment in control and openness. It takes planning and some engineering work, but the payoff is enduring: reduced vendor dependence, better privacy controls, and an extensible platform you control. If you want, I can share the specific scripts and configs we used for converting Slack exports and for setting up the Synapse Helm chart on Kubernetes.