Mattermost vs Rocket.Chat

Both Mattermost and Rocket.Chat exist to answer the same question: how do you leave Slack without handing your team's entire conversation history to someone else's cloud? They are the two heavyweight open-source answers, and they are genuinely close on the things that matter day to day — channels, threads, DMs, mobile apps, and integrations. The real decision is not features on a comparison grid but temperament: do you want a fast, focused chat app that feels like the Slack your team just left, or a single platform that folds voice, video, and customer messaging into one deployment?

Two philosophies of "team chat"

Mattermost takes the focused route. It is, deliberately, a very good chat application: channels and threads, a clean and quick web client, a solid mobile app, slash commands, webhooks, and a plugin system for the extras. The experience is close enough to Slack that most people migrating never have to relearn how they work, and the product stays lean because messaging is the main event rather than one tab among many.

Rocket.Chat takes the platform route. Out of the box it is not just chat but a communications hub: built-in voice and video, an omnichannel module that turns the same inbox into a customer-support channel across the web, email, and messaging apps, plus a large marketplace of apps and integrations. If your goal is "one place for internal chat and talking to customers," Rocket.Chat wants to be that place without a second product bolted on.

Neither approach is wrong. They optimize for different owners — one for a team that wants Slack-without-Slack, one for an organization that wants a single messaging platform to run several conversations at once.

The stack difference is the operational story

This is where the two diverge most for a self-hoster. Mattermost is a compiled Go server with a React front end, backed by PostgreSQL. That means a single static binary (or one lean container) plus a boring, well-understood relational database — a stack most people running a VPS already know how to back up, tune, and upgrade.

Rocket.Chat is a Node.js application built on MongoDB, and in practice it wants MongoDB configured as a replica set even for a single-node install because it relies on the oplog to push messages in real time. That is entirely workable — the official Compose file sets it up for you — but it is a heavier, less familiar moving part than Postgres, and MongoDB is the piece most likely to need attention as your data grows. If you are comfortable operating Mongo, this is a non-issue; if you are not, it is the single biggest reason a Rocket.Chat box needs more babysitting over time.

Feature-by-feature

• Everyday chat — a near tie. Channels, threads, DMs, reactions, search, and file sharing are all solid on both. Mattermost feels a touch snappier and more Slack-like; Rocket.Chat exposes more knobs.
• Voice and video — built in on Rocket.Chat. Mattermost handles calls through a plugin (its Calls plugin) rather than shipping it as a core feature, so it works but feels more like an add-on.
• Omnichannel / customer messaging — a Rocket.Chat specialty with no direct Mattermost equivalent. If you want to talk to customers and colleagues from one server, this is the differentiator.
• Integrations and bots — both have webhooks, slash commands, and app ecosystems. Mattermost leans developer-workflow (CI, incident response); Rocket.Chat leans breadth of connectors.
• Migrating from Slack — both import Slack exports, but Mattermost's interface is the closer visual and behavioral match, which shortens the "where did everything go" phase for a switching team.

Resources and performance

The spec table rates both at the same 2 GB RAM floor and the same 3/5 difficulty, and that is fair — neither is a lightweight you run next to a dozen other services on a 1 GB box. The difference is not the number on the sheet but what fills it. Mattermost's Go binary is frugal and predictable under load, and Postgres behaves the way you expect. Rocket.Chat's Node plus MongoDB combination tends to sit higher at idle and is more sensitive to how Mongo is configured. Give either real headroom once a team actually lives in it, but expect Mattermost to stay lighter for the same number of active users.

Licensing

Worth a note because it cuts against the usual grain: Rocket.Chat is MIT licensed, one of the most permissive licenses there is, while Mattermost's core server is AGPL-3.0, a strong copyleft license. For a team simply running either on its own VPS this rarely changes anything — you can self-host both freely — but if you intend to build a product on top of the code and redistribute it, the MIT terms are the more permissive starting point.

Which should you self-host?

Pick Mattermost if…

• You want a fast, Slack-like chat your team adopts with almost no relearning, and messaging — not a platform — is the point.
• You would rather operate a Go binary on PostgreSQL than run and maintain a MongoDB replica set.
• You value predictable resource use and a clean upgrade path for a stack you probably already know.

Pick Rocket.Chat if…

• You want built-in voice and video and omnichannel customer messaging in one deployment, not a chat app plus separate tools.
• The broad app marketplace and deep configurability appeal to you more than a lean, opinionated core.
• You are comfortable running Node and MongoDB, and the permissive MIT license matters for how you plan to use or extend the code.

Running either on a VPS

Both run comfortably on a single small server — plan for 2 GB of RAM as a realistic starting point and give whichever you choose more headroom as active users climb. The practical gap is operational: Mattermost's Go-and-Postgres stack tends to stay lighter and asks less of you over time, while Rocket.Chat's Node-and-MongoDB setup wants a little more care, especially around the database. The step-by-step setups are linked below, and any of the VPS options here has plenty of room for the app plus its database.