Last checked October 2026 · 10 alternatives to Slack in our catalog
Slack paid plans start at $7.25/user/mo, which is why people look for an open-source alternative. Below are 4 open-source options you can inspect, modify and often self-host - 2 are completely free, 3 run on Linux and 3 work in the browser.
Picked from listing data (price model, license, platforms, community votes), not hands-on testing.
| Alternative | Price | Open source | Platforms | What it is |
|---|---|---|---|---|
| Zulip | Free | Yes | Web, Android, iOS | Open-source team chat organized around topic threads |
| Mattermost | Contact for Pricing | Yes | Web, Windows, Mac, Linux | Secure, self-hosted team messaging and collaboration. |
| Rocket.Chat | Freemium | Yes (Other) | Web, Windows, Mac, Linux | Secure CommsOS for mission-critical operations |
| Signal | Free | Yes (AGPL-3.0) | Windows, Mac, Linux, iOS | Private, end-to-end encrypted messaging. |
Open-source team chat organized around topic threads
Secure, self-hosted team messaging and collaboration.
Secure CommsOS for mission-critical operations
Free plan includes: Unlimited users · Self‑hosted deployment · Basic chat and collaboration tools · Community support
Private, end-to-end encrypted messaging.
Zulip is the first free alternative we list for Slack and has no paid tier. Others worth a look: Mattermost, Rocket.Chat and Signal. Which one fits depends on what you use Slack for, so check the platform and free-plan details for each.
Yes: Zulip, Mattermost, Rocket.Chat and Signal. Open-source options can usually be inspected, modified and self-hosted.
Yes. The free plan includes 1:1 huddles, Limited app integrations and 10 integrations. Paid plans start at $7.25/user/mo.
How this list is built: alternatives come from our catalog's curated alternative relationships; price model, license and platforms come from each product's listing; order is fully-free first, then community votes.
