# Free alternatives to Slack

> Slack (Pro) costs $87 a year. Free alternatives: Mattermost, Rocket.Chat and Zulip. Data checked 2026-10-17.

- Page: https://stoprenting.dev/apps/slack/
- Category: Team Chat (https://stoprenting.dev/categories/team-chat/)
- Vendor: Salesforce
- Plan: Pro
- Price: $7.25/month, $87/year
- Billing: per user, paying annually ($8.75 monthly)
- Price quote from the vendor's page: "$8.75 USD per user / month, when paying monthly $7.25 USD per user / month, when paying annually"
- Price source: https://slack.com/pricing (checked 2026-10-17)

## Alternatives

### Mattermost

- Website: https://mattermost.com
- Repository: https://github.com/mattermost/mattermost (39,357 stars, last push 2026-10-17)
- License: AGPL-3.0 source / MIT compiled
- Open source: yes, OSI-approved license
- Type: server app
- Linux: self-hosted server; web UI
- Self-hostable: yes
- More: https://stoprenting.dev/alternatives/mattermost/
- Checked: 2026-10-17

### Rocket.Chat

- Website: https://www.rocket.chat
- Repository: https://github.com/RocketChat/Rocket.Chat (46,270 stars, last push 2026-10-13)
- License: MIT (ee/ proprietary)
- Open source: yes, OSI-approved license
- Type: server app
- Linux: self-hosted server; web UI
- Self-hostable: yes
- More: https://stoprenting.dev/alternatives/rocket-chat/
- Checked: 2026-10-17

### Zulip

- Website: https://zulip.com
- Repository: https://github.com/zulip/zulip (26,029 stars, last push 2026-10-12)
- License: Apache-2.0
- Open source: yes, OSI-approved license
- Type: server app
- Linux: self-hosted server; web UI
- Self-hostable: yes
- More: https://stoprenting.dev/alternatives/zulip/
- Checked: 2026-10-17

## FAQ

### Is there a free alternative to Slack?

Yes. The 3 free alternatives are Mattermost (open source, AGPL-3.0 source / MIT compiled), Rocket.Chat (open source, MIT) and Zulip (open source, Apache-2.0).

### How much does Slack cost?

Slack's Pro plan costs $7.25 a month, which is $87 a year (per user, paying annually ($8.75 monthly)). Source: the official pricing page at slack.com, checked Oct 17, 2026.

### Which Slack alternatives run on Linux?

Mattermost (self-hosted server; web UI), Rocket.Chat (self-hosted server; web UI) and Zulip (self-hosted server; web UI).

### Can you self-host a Slack alternative?

Yes. Mattermost, Rocket.Chat and Zulip run on your own server.

### Are these Slack alternatives open source?

Yes. All 3 use OSI-approved open-source licenses: Mattermost (AGPL-3.0 source / MIT compiled), Rocket.Chat (MIT) and Zulip (Apache-2.0).

---
Source: Stop Renting (https://stoprenting.dev). Methodology: https://stoprenting.dev/methodology/