Self-hostable open-source Slack alternatives
Team messaging. Self-hosted chat gives data sovereignty and removes per-user costs for larger teams.
Among 3 self-hostable open-source Slack alternatives tracked here, Rocket.Chat currently leads on the Self-Host Health Score (100/100, 45k★, last commit today). For a Raspberry Pi or a low-RAM VPS, Mattermost is the lightest at a documented ~2048 MB (PostgreSQL). 1 of them publish official ARM64 images (Raspberry Pi / Apple Silicon). 3 offer a one-click deploy (e.g. Railway, DigitalOcean, Render).
| Tool | Health | Stars | Database | Min RAM | ARM/Pi | One-click | Updated |
|---|---|---|---|---|---|---|---|
| Rocket.Chat
↗
Feature-rich team chat with omnichannel + federation. |
100 Thriving |
45k★ TypeScript |
MongoDB | 4096 MB | ✓ ● | Railway ↗ | today |
| Mattermost
↗
Enterprise-grade self-hosted Slack alternative for ops/dev teams. |
99 Thriving |
37k★ TypeScript |
PostgreSQL | 2048 MB | ✗ ● | DigitalOcean ↗ Railway ↗ | today |
| Zulip
↗
Threaded team chat that scales to large async communities. |
98 Thriving |
25k★ Python |
PostgreSQL | 2048 MB | ✗ ● | DigitalOcean ↗ Render ↗ | today Apache-2.0 |
FAQ
What is the best self-hostable Slack alternative?
By the live Self-Host Health Score, Rocket.Chat ranks highest (100/100).
Which open-source Slack alternatives run on a Raspberry Pi?
Those publishing official ARM64 images: Rocket.Chat.
Which is the lightest on RAM?
Mattermost, at about 2048 MB.