Slack Pro alternatives: 5 open-source picks
Slack Pro costs $8.75/mo — $105 a year. These 5 alternatives replace it for $0, led by Rocket.Chat Community, Mattermost Team Edition and Zulip. All 5 are open source. License, stars and last commit checked by hand on 2026-08-29. No trials, no crippled tiers.
Channels, threads, files and integrations for up to a hundred concurrent users; MongoDB is the hidden teammate.
licenseMIT
runsyour server
installDeploy the Community workspace with Docker Compose, Podman, or Kubernetes
dataUsers, rooms, messages, and most metadata live in MongoDB; uploads live on local storage or a configured object-storage backend.
the catch vs Slack ProRocket.Chat Community covers channels, threads, files, and integrations, but it adds MongoDB operations, a 100-concurrent-user limit, and a much smaller ecosystem than Slack.
setupA production installation requires MongoDB, DNS/TLS, email, backups, upgrades, and enough capacity planning to stay within the Community plan's 100-concurrent-user limit.
facts verified 2026-08-10
Slack-shaped chat below 250 users, self-hosted; the subscription disappears and the pager appears.
licenseMIT
runsyour server
installInstall the official Linux binary with PostgreSQL, then configure systemd, TLS/reverse proxy, SMTP, and file storage
dataChannels, posts, users, and configuration live in PostgreSQL; file attachments live in the Mattermost data directory or configured S3-compatible object storage.
the catch vs Slack ProMattermost Team Edition closely resembles Slack, but self-hosting adds database, email, storage, backup, upgrade, and uptime work while enterprise identity and compliance remain paid.
setupThe first obstacle is a real Linux service deployment, PostgreSQL, SMTP, DNS/TLS, storage, backups, and upgrades, not an app-store install.
facts verified 2026-08-10
Topic-first team chat with full history and excellent search; fewer drive-by messages survive.
Rooms, threads, files and encrypted calls on Matrix; the free public service avoids server duty.
licenseAGPL-3.0-or later OR GPL-3.0+
runsyour machine or their cloud
installUse a free Matrix account in Element Web/mobile/desktop, or deploy Element Server Suite on your own infrastructure
dataRooms, event history, account data, and media live on the selected Matrix homeserver; encrypted-room keys remain on clients and can be backed up through Matrix's key-backup system.
the catch vs Slack ProElement provides rooms, threads, files, calls, and encryption, but Matrix is less familiar and its workplace app and integration ecosystem is much smaller than Slack's.
setupThe clean hosted path is easy, but self-hosting the current Element Server Suite means operating a Matrix homeserver and its Kubernetes/Helm-based stack.
facts verified 2026-08-10
The internet's civilized discussion platform — modern forums with trust levels and rich moderation.
licenseGPL-2.0
runsyour server
setupnot verified by us yet — check the repo README
facts verified 2026-08-29
What each one is, in full: Rocket.Chat Community · Mattermost Team Edition · Zulip · Element · Discourse
last updated 2026-08-29 · no votes, no pay-to-list · just what's real
how to choose a Slack Pro alternative
Easiest to get running
Element — they host it, so there is nothing to install.
Most proven
Rocket.Chat Community, with 45,900 GitHub stars — the largest community of the 5, which usually means more answers when something breaks.
Works on your phone
Rocket.Chat Community has a mobile app on iOS and Android.
Needs real ops to self-host
Rocket.Chat Community, Mattermost Team Edition and Zulip are capable but expect someone to run a server, updates and backups. Budget for that before choosing one.
what you give up by leaving Slack Pro
- existing team network, integrations, push delivery, enterprise controls, and global reliability
- network effects
- native mobile apps
- video and voice infrastructure
- enterprise moderation and discovery
None of the picks above covers all of it. The full verdict says which gaps matter.
Slack Pro alternatives at a glance
| tool | license | running it | platforms | stars | active |
|---|---|---|---|---|---|
| Rocket.Chat Community | MIT | self-host, real ops | web, macos, windows, linux, ios, android, self-hosted | 45,900 | 2026-08 |
| Mattermost Team Edition | MIT | self-host, real ops | web, macos, windows, linux, ios, android, self-hosted | 38,700 | 2026-08 |
| Zulip | open source | self-host, real ops | web, macos, windows, linux, ios, android, self-hosted | 25,600 | 2026-08 |
| Element | AGPL-3.0-or later OR GPL-3.0+ | they host it | web, macos, windows, linux, ios, android, self-hosted | 13,300 | 2026-07 |
| Discourse | GPL-2.0 | docker to self-host | self-hosted, web | 44,000 | 2026-08 |
why people still pay for Slack Pro
People still pay for Slack Pro because community software is valuable when members are already there and the operator does not have to own realtime reliability and abuse response. The recurring cost buys realtime delivery, notifications, abuse handling, search, media, permissions, mobile clients, backups, and community operations, not just the visible interface. If none of that applies to you, any pick above saves $105 a year.
questions about switching from Slack Pro
Is there an open-source alternative to Slack Pro?
Yes: Rocket.Chat Community, Mattermost Team Edition, Zulip and 2 more. Every tool on this page is open source: no trials, no crippled tiers.
Can open source really replace Slack Pro?
Our verdict is YES. Rocket.Chat Community (46k stars), Discourse (44k stars), Mattermost Team Edition (39k stars) are mature open-source replacements for Slack Pro — self-host with real ops work and stop paying $8.75/mo. The full verdict, and what you give up by switching, is at caniopensourceit.online/slack-pro.
What is the easiest open-source Slack Pro alternative to set up?
Element — they host it, so there is nothing to install.
What is the most popular open-source Slack Pro alternative?
By GitHub stars, Rocket.Chat Community (45,900). Discourse is next with 44,000.
