Open Source Chat

Start with conversation structure: rooms, direct messages, threads, federation, and history. These choices shape daily behavior more than theme support or admin screens. A tool that handles small team rooms well may struggle with large public channels, and a federated system may add overhead you do not need. Match the model to how your organization actually talks.

Self-hosting makes sense when chat history, identity, or network boundaries need to stay under your control. It also means you own uptime, upgrades, storage growth, abuse prevention, and push notification setup. For a small team without infrastructure experience, managed hosting may be more practical. For regulated or infrastructure-heavy teams, self-hosting can be a reasonable trade.

End-to-end encryption protects message content from the server, but it affects search, moderation, compliance review, bot access, and account recovery. Some systems encrypt only direct messages, while others support encrypted rooms. Test device enrollment, lost-device recovery, and message search before relying on it. Strong privacy is useful only if users can still operate the system correctly.

Mobile support is a make-or-break detail for chat. Check whether the project has maintained iOS and Android clients, how push notifications are delivered, and whether self-hosted deployments require extra gateway configuration. Also test mentions, muted rooms, background sync, and attachment handling. A chat server can be solid while the mobile experience still frustrates everyone.

Migration difficulty depends on what your current system exports. Basic messages and users may transfer, but threads, reactions, edits, files, private channels, deleted content, and timestamps often need cleanup. Identity mapping is usually the hardest part if emails, usernames, or external accounts changed over time. Run a trial import with real data before announcing a cutover date.

Look beyond owner and member roles. Real teams need channel-level permissions, guest access, private rooms, moderation actions, invite controls, and limits on who can create integrations or mass-mention users. If contractors, customers, or community members will share the same server, separation rules matter. Weak permissions usually show up later as messy workarounds.

Prioritize integrations that match your workflow instead of counting connectors. Webhooks, bot APIs, OAuth, command handling, and notification routing are usually more important than a long catalog. Engineering teams often need issue tracker, CI, monitoring, and deployment alerts. Also check permission boundaries so a bot cannot read more rooms or user data than it needs.

Chat history becomes valuable quickly, but unlimited retention can create cost, privacy, and legal risk. Check whether retention policies can differ by room type, whether deleted messages are actually removed, and how file attachments are handled. Search should work across large rooms without making the server sluggish. If encrypted rooms are required, confirm what search still supports.

Federation matters when separate organizations, communities, or departments need to communicate while keeping their own servers and policies. It is less useful for a single company that only needs internal collaboration. Federated chat adds questions around identity trust, room discovery, abuse handling, and delivery reliability. Choose it for a real boundary problem, not because it sounds more open.

Back up the database, uploaded files, configuration, encryption keys if applicable, and identity provider settings. A database dump without attachments or keys may not restore usable conversations. Test restoration into a separate environment and verify logins, rooms, files, and search indexes. Chat is often mission-critical during incidents, so backup plans should be proven before failure.

Your risk depends on the data format, deployment complexity, and how replaceable the clients are. Prefer systems with documented exports, standard authentication options, and clear server configuration. Keep periodic exports even if you are happy with the tool. If development slows, you want time to patch, fork, migrate, or move to hosted support without losing history.