Element vs Mattermost

The one question that decides this

Element vs Mattermost is not really a fight over “which open-source Slack clone has channels.” It is a fight over philosophy. Element is trying to be secure decentralized communication built on Matrix, with Slack and Signal both in its replacement blast radius. Mattermost is trying to be a secure, open-source messaging platform for enterprises, replacing Slack and Microsoft Teams. If you want federation and a Matrix-centered model, Element is the more natural fit; if you want an enterprise collaboration platform that feels closer to the Slack/Teams procurement lane, Mattermost is the cleaner bet.

What each one is actually trying to be

Element: secure decentralized communication built on Matrix

Element’s own tagline is “Secure decentralized communication built on Matrix,” and that is the whole plot. It is not merely trying to be a chat app with an open-source badge slapped on the README. The GitHub description calls it “A glossy Matrix collaboration client for the web,” which is refreshingly direct: Element is the client face of a broader Matrix world, not a sealed company chat island pretending openness is a pricing tier.

That makes Element more ambitious than a normal Slack alternative, and also more opinionated. Its replacement list includes both Slack and Signal, which tells you it is aiming at the overlap between workplace collaboration and secure messaging. That is a different posture from “we rebuilt Slack, but you can host it.” Element is for teams that care about the communication substrate, not just the chat UI. That can be powerful, but it also means you are buying into Matrix as a model, with all the operational and organizational implications that come with choosing a decentralized stack.

Mattermost: secure, open-source messaging platform for enterprises

Mattermost’s tagline is “Secure, open-source messaging platform for enterprises,” and that reads like it was written with an IT buyer, not a protocol nerd, in mind. The GitHub description says: “Mattermost is an open source platform for secure collaboration across the entire software development lifecycle..” The double period is doing more brand work than it should, but the positioning is clear enough. Mattermost wants to be the serious enterprise collaboration system you can run yourself.

Its replacement targets are Slack and Microsoft Teams, which is a much more conventional lane than Element’s Slack-plus-Signal framing. Mattermost is not trying to sell you on decentralization as the core idea. It is trying to give organizations a secure collaboration platform with open-source availability and self-hosting as part of the pitch. That makes it feel more directly comparable to Slack for workplace use, especially for teams that want less SaaS dependency without turning their chat decision into a federation discussion.

Head-to-head: the metrics

On GitHub, Element’s element-hq/element-web repository has 13347 stars, 2710 forks, 3834 open issues, license AGPL-3.0, last push 2026-08-05, and the primary language is TypeScript. Mattermost’s mattermost/mattermost repository has 38680 stars, 8879 forks, 968 open issues, license NOASSERTION, last push 2026-08-05, and the primary language is TypeScript. Both projects look alive from the last-push date alone. Neither is some abandoned “open source Slack alternative” repo from 2017 with a Docker Compose file and a dream.

The star and fork gap is not subtle. Mattermost has far more GitHub stars and forks: 38680 stars vs Element’s 13347, and 8879 forks vs Element’s 2710. That suggests Mattermost has had a larger developer-facing footprint on GitHub, or at least a broader audience interacting with that repository. Stars are not adoption, revenue, happiness, or maintainability. They are a popularity signal, and a noisy one, but when the gap is this large it is still worth noticing.

The issue count points in the other direction. Element shows 3834 open issues, while Mattermost shows 968 open issues. That does not automatically mean Element is worse maintained. A project can have more issues because it has a larger surface area, more public triage, a more active user base, or a different issue-management culture. But it does mean a prospective self-hoster should not hand-wave the number away. Open issues are not a verdict, but 3834 is not a decorative integer.

Licensing is also a real distinction in the provided data. Element is listed as AGPL-3.0, which is explicit and meaningful for organizations that care about copyleft obligations around network software. Mattermost is listed as NOASSERTION, which is not the same thing as “no license” and not the same thing as a clean legal green light. It means the provided GitHub license field is not asserting a license here. If license posture matters to your company, that is not a vibes-based decision; legal needs to look at the actual repository and product terms.

What these metrics tell us: both projects are active, both have substantial GitHub footprints, and Mattermost has much larger visible GitHub popularity while Element has a much larger open issue count in the supplied data. What they do not tell us: whether either product will fit your compliance model, whether your users will like the UX, whether mobile push will behave the way your company expects, or whether your admins will enjoy the next six months of ownership. GitHub numbers are useful smoke signals. They are not a migration plan.

Self-hosting

Element supports self-host and official-cloud hosting options, with a deploy difficulty of 4 out of 5. That tracks with the product’s broader shape: you are not just choosing a workplace chat skin, you are stepping into the Matrix ecosystem. For teams that value decentralized secure communication, that complexity may be acceptable or even the point. For teams that just want to stop paying Slack without turning chat into infrastructure homework, a 4 out of 5 difficulty rating is the warning label.

Mattermost also supports self-host and official-cloud, but its deploy difficulty is 2 out of 5. That is the practical differentiator for a lot of teams. The project is positioned as an enterprise messaging platform, and the lower deploy difficulty suggests a more straightforward path for organizations that want self-hosted collaboration without adopting a new communication philosophy wholesale. It still needs operating, upgrading, backups, identity integration, and all the other glamorous chores that make self-hosting real. But in this comparison, Mattermost is clearly the easier self-hosting candidate based on the provided difficulty scores.

Community signals

Element has 1 Hacker News mention in the last 90 days. Its top provided HN story is “Element (Matrix chat app) suspended from the Google Play Store,” posted by redsolver on 2021-01-29T23:28:33Z, with 2009 points and 940 comments. That is a large discussion, though the story is about a store suspension rather than a calm product evaluation. The provided Reddit top post for Element is from r/interestingasfuck: “This scientist blends diverse chemical elements and reactions to generate mesmerizing visuals that materialize within a single drop of water,” with 35635 upvotes and 331 comments. That is clearly about chemical elements, not Element the chat product, so treating it as product sentiment would be SEO-brained slop.

Mattermost has 0 Hacker News mentions in the last 90 days. Its top provided HN story is “Mattermost: Open-source, on-premises, Slack alternative,” posted by aviv on 2015-06-24T08:21:34Z, with 432 points and 216 comments. That is old, but at least it is directly about the product and its core pitch. The provided Reddit top post for Mattermost is “cachyos+new cosmic 1.3.0” from r/cachyos, with 490 upvotes and 39 comments. That does not appear to be about Mattermost as a Slack alternative, so it should not be laundered into “Reddit loves Mattermost.” It is just present data with weak relevance.

What we'd do

Pick Element if the real requirement is secure decentralized communication and Matrix is part of the strategy, not an accidental dependency someone discovers during deployment week. It is the more philosophically distinct Slack replacement, and the AGPL-3.0 license is explicit in the provided data. Pick Mattermost if the job is replacing Slack for an organization that wants open-source, self-hostable enterprise messaging with less deployment pain. Mattermost has the bigger GitHub footprint here, a lower deploy difficulty, and a pitch that maps more directly onto the Slack-shaped hole most companies are actually trying to fill.