Self-Hosted Slack Alternative for a Community

If your Slack community is losing old messages and the bill grows with every person you invite, you can run your own. There are two different kinds of software to look at. Zulip, Mattermost and Rocket.Chat are team-chat applications you install on a server. BuddyNext is a WordPress plugin that gives you a member community on a site you own. They solve overlapping problems, and the right one depends on what your group actually does all day.

This guide tries to be fair about that. We build BuddyNext, so we will say plainly when one of the chat tools is the better choice.

Why does the Slack free plan lose messages after 90 days?

It is a deliberate limit on the free plan, not a bug. Slack’s help centre article on the free plan states that you are limited to the most recent 90 days of message and file history. The same article says that if you upgrade, the messages and files beyond that limit are revealed again.

There is a harder edge as well. The article says data in a free workspace that is more than one year old is deleted, and that this started on 26 August 2024. So the old material is first hidden, and later gone. We read that page on 31 Oct 2026. Slack changes its plans from time to time, so check the current wording on slack.com before you make a decision on our summary.

That matters differently depending on what your community is. If it is a project team and last quarter’s chatter has no value, you may never notice. If it is a group of members who ask questions, share resources and build relationships over years, the history is the asset. Losing it means new members cannot find what the group already worked out, and the same question gets asked every month.

The second complaint, per-seat pricing, is built into how Slack sells. Each active person is a seat, so a community that grows from fifty to five hundred members grows its invoice with it. We are not quoting numbers here because they change; the shape is what matters. The cost follows head count, not the value you get.

What does a self-hosted Slack alternative look like?

Self-hosting means the software runs on a server you control and the messages sit in a database you control. Nobody else decides how far back you can read. The trade is that the upkeep becomes yours, or your host’s.

That upkeep is ordinary website work:

• Hosting. You pay a host. The bill follows your traffic and storage, not your member count in a seat-by-seat way, though a busy site eventually needs a bigger plan.
• Updates. The application, its add-ons and the server underneath all need patching. Skipping updates is how self-hosted sites get into trouble.
• Backups. Copy the database and uploaded files on a schedule, store them somewhere other than the same server, and restore one to a test copy now and then. A backup you have never restored is a hope.
• Email. Notifications and invitations leave through your server, so use a proper mail-sending service and test delivery before launch.

Slack does all of this for you. If you do not want that job, say so honestly, and consider a managed host that handles the patching. For a longer look at the question, see our post on self-hosted vs hosted community platforms.

The software choice splits into two shapes. The first shape is a chat tool, the closest thing to Slack. The second is a community site, where the unit is a member and a space rather than a channel and a message. Here are the options.

Where does Zulip win?

Zulip is the strongest answer if your problem is that Slack threads get messy. Every conversation in Zulip is organised under a topic, so you start a message by giving it a short topic and replies stay attached to it. Zulip’s own site describes this as topic-based threading that combines the best of email and chat, and calls threads first-class.

Why that matters to a community: people who are in a different time zone can catch up on a conversation by topic rather than reading a scrolling wall. Zulip also keeps its history searchable. The project is open source, and its repository says it is distributed under the Apache 2.0 license. You can self-host it directly on Ubuntu or Debian, with Docker, or with prebuilt images, and there is a hosted Zulip Cloud if you would rather not run it.

Pick Zulip when your group is a team or a technical community that talks all day and wants better thread discipline than Slack gives. It is a chat tool through and through. It does not give you a public-facing profile directory, a social feed, or a membership site around it.

For the side-by-side, see BuddyNext vs Zulip and the Zulip alternative page.

Where does Mattermost win?

Mattermost is built for organisations that want Slack-like channels with control over where the data lives. Its pricing page describes deployment on your own infrastructure, including Kubernetes and air-gapped environments, and it also offers a cloud service run by Mattermost. That makes it a common pick for engineering teams, public-sector groups and anyone with strict security or compliance rules.

On licensing, be careful and read the repository yourself. Its README calls Mattermost an open-core platform and says a compiled version is released under an MIT license every month. The repository also carries a separate enterprise license file. The paid editions are sold as annual subscriptions per seat, and the pricing page notes each Mattermost server needs its own license. Check mattermost.com for what each edition includes today, because that is the part most likely to change.

Pick Mattermost when you want a Slack replacement for a team, you need strong deployment and security options, and you are comfortable with an open-core model where some features sit in paid editions. If your reason for leaving Slack is per-seat pricing, read the edition list carefully, because Mattermost’s paid tiers are priced per seat too.

For the side-by-side, see BuddyNext vs Mattermost and the Mattermost alternative page.

Where does Rocket.Chat win?

Rocket.Chat is team chat that also reaches outward. Besides internal channels it is known for customer-facing messaging, where support conversations arrive from several channels into one place. Its repository carries an MIT badge and a separate ee folder for enterprise code, and its README tells you to deploy on your own servers with Docker, Podman or Kubernetes. Its pricing page describes a free self-managed workspace you can deploy to try it, alongside commercial plans that include on-premises, private cloud and fully air-gapped deployment.

The split between the free workspace and the paid plans is not spelled out in one place, and the ee folder carries its own terms. If you are choosing Rocket.Chat, read its license file and the feature list for the edition you plan to run before you commit.

Pick Rocket.Chat when your community sits close to customer support or when you need chat across several external channels as well as inside the team.

For the side-by-side, see BuddyNext vs Rocket.Chat and the Rocket.Chat alternative page.

Where does BuddyNext fit?

BuddyNext is a WordPress plugin from Wbcom Designs. It is for the case where your Slack workspace is really a community: members who join, introduce themselves, ask each other things, and belong to groups. It is newer than every product above, and it is not a chat tool. We would rather tell you that now.

Here is what the documentation supports, in the free core:

• Spaces. Groups with three privacy types. Open spaces can be found and joined by anyone, Private spaces are listed but require approval and keep content members-only, and Secret spaces are hidden and invite-only.
• An activity feed. Posts, comments, reactions, polls, hashtags, mentions and bookmarks, with unified search across members, posts, spaces and hashtags.
• Member profiles and a directory. Profile fields, following, an online-now indicator and a recently-active sort in the directory.
• Notifications and digests. An in-site notification bell, and member-chosen daily or weekly email digests.
• Moderation. A reporting flow, a moderation queue and a moderation log.
• Direct messages. One-to-one conversations with typing indicator, in-thread search, per-conversation mute and media sharing. These run on the free WPMediaVerse companion plugin, which stores and delivers the messages.
• Privacy tools. Members can export their own data or delete their account, and you can put the whole community behind a login.
• A REST API and one outbound webhook destination.

Two of these answer the 90-day problem directly. Content in a space is a post with its own place and address, so it does not scroll off into a history limit. And BuddyNext has no setting that expires your posts or messages. The retention options live under Members, then Privacy & Data, and cover closed moderation reports, how long read notifications and email logs are kept, and, with Pro, analytics events. They do not touch member profiles, posts or messages.

What does BuddyNext not do like Slack?

This section matters more than the one above if you are deciding.

There are no channels and threads in the Slack sense. A space has a feed, with comments under each post. For titled, durable threads and Q&A, a space can have an optional Discussions tab, which is powered by the Jetonomy companion plugin. It adds voting, accepted answers and search. That is a forum model, not a live chat room.

Free is not instant. The notification bell refreshes about every 30 seconds when idle, and for a minute after you act it checks every 5 seconds. The feed checks for new posts about once a minute and shows a pill you click. Direct messages on the free engine surface through the bell on a short interval, not the instant they are sent. If your members expect to type and see a reply in two seconds, free BuddyNext will feel slow.

Real-time is Pro, and you supply a server. BuddyNext Pro can connect to a WebSocket server over the Pusher protocol. Sockudo is the free, self-hosted recommendation in the docs, and hosted Pusher-compatible services also work. Once it is connected, reactions, comments, new posts and notifications arrive immediately. If the server drops, the community falls back to polling. Instant delivery for direct messages also relies on WPMediaVerse Pro, as do read receipts and group messages.

No group chat on the free plan. Free direct messaging is one-to-one. A conversation between more than two people needs WPMediaVerse Pro.

No audio or video calls built in. We have not found calls documented, so we are not claiming them. Many communities pair a community site with a separate meeting tool.

So the honest summary is that BuddyNext replaces what a Slack community was used for as a place to belong, find people, post and keep a record. It does not replace Slack as a fast, always-on chat room.

Free and Pro, stated plainly

Everything in the list above under the free core works without a key and nothing in it expires. Pro is a paid licence that covers updates and support and adds features. The ones relevant to a Slack-style community are:

• Real-time WebSocket transport, as described above.
• Browser push notifications through Firebase, so a member sees a banner when the site is not open.
• Broadcast email and drip sequences.
• Membership plans and gated spaces, if you want to charge for access.
• Bulk moderation, advanced member filters in search, and unlimited webhook destinations.

We do not list prices on this page because they change. The pricing page has the current terms, and it is the only source we would trust over this page.

How do the options compare for a community?

This table sticks to the questions that decide a move away from Slack.

A fair reading of that table: the three chat tools give you the closest feel to Slack. BuddyNext gives you the part Slack never offered, a site that members and the public can browse, and a place where a post stays a post.

Which one should you choose?

Work down the list and stop at the first line that fits you.

1. Your group is an internal team and chat is the work. Choose Zulip or Mattermost. If you want better threading, lean Zulip. If you need a deployment story for a security team, lean Mattermost.
2. You also run customer conversations across several channels. Look at Rocket.Chat.
3. Your Slack is a community of members who need to find each other and old answers, and you already run WordPress or are happy to. Choose BuddyNext.
4. You need instant, always-on chat and a community site. Use both. Run a chat tool for the live talk and BuddyNext for the record. Many communities end up here.
5. You want zero upkeep and do not mind the limits. Stay on a hosted plan. That is a fair answer.

If you would like the direct comparison with Slack itself, see BuddyNext vs Slack or the Slack alternative page. For the wider view across community software, our guide to the best self-hosted community platform covers Discourse, HumHub, BuddyPress and BuddyBoss as well.

How do you move a Slack community across?

There is no one-click importer for Slack in BuddyNext, and we will not pretend otherwise. The practical path is an export, an invitation and a rebuild of structure.

• Export what you are allowed. Check Slack’s export options for your plan. Free workspaces only export what is still visible, so do this before more history disappears.
• Decide what is worth keeping. Pull out the answers, guides and links people actually reuse. Reposting a curated set into spaces, or into a Discussions tab, is usually better than copying everything.
• Map channels to spaces. A public channel for introductions becomes an open space. A private channel becomes a private or secret space.
• Invite members. BuddyNext supports bulk invitations by CSV on the Invites tab, and share links for spaces.
• Run both for a few weeks. Keep the Slack workspace read-only for a while and point people to the new address.

If you used a Slack integration to post into a channel, BuddyNext’s outbound webhook can send community events to a Slack channel, which helps during the overlap. The free plan allows one destination.

What do you need before installing BuddyNext?

Check these before you pick a date.

The plugin sets itself up on activation and has a Tools and Maintenance screen that tells you if background tasks, the object cache or the search index have fallen behind. For a large, busy community, a persistent object cache such as Redis or Memcached keeps the heavy lists quick. It is a recommendation, not a requirement. For direct messages, install the WPMediaVerse companion; BuddyNext can install the free companions from its Add-ons screen.

The Pro licence key gates updates only. It never switches features off, so an expired key does not lock you out of anything you already use.

A short checklist before you leave Slack

• Export what your plan lets you export, and do it soon, because the visible window keeps moving.
• Restore a backup of the new site to a test copy at least once.
• Send a test invitation and a test notification email to a real inbox, and check the spam folder.
• Set a privacy type for every space before anyone joins.
• Decide your data rules: whether members can export or delete their own data, and whether the community is public or behind a login.
• Tell members what is changing, where the old answers went, and when the old workspace goes read-only.

None of this is glamorous, but it is what makes a self-hosted move go smoothly. The value of leaving a hosted chat tool is that your community’s memory belongs to you. Pick the shape of software that matches how your group really behaves, and be honest about whether that is a chat room or a place.