#1 · 83% match
Mattermost
- Application type
- Chat & community apps
- Origin
United States- Platforms
- Web
- Windows
- macOS
- Linux
- Android
- iOS
Free + paid
Visit site 6 Best Open-Source Slack Alternatives (2026)
Slack: workplace messaging with channels, huddles and app integrations. Of the 10 alternatives we track, 6 match the "Open source" filter. Mattermost is the closest match, sharing 83% of Slack's tracked features and platforms. Every option links to its own alternatives, so you can keep exploring.
Last reviewed October 20, 2026 · 6 alternatives
#2 · 75% match
Element
- Application type
- Chat & community apps
- Origin
United Kingdom- Platforms
- Web
- Windows
- macOS
- Linux
- Android
- iOS
Free + paid
Visit site #3 · 75% match
Zulip
- Application type
- Chat & community apps
- Origin
- United States
- Platforms
- Web
- Windows
- macOS
- Linux
- Android
- iOS
Free + paid
Visit site #4 · 67% match
Rocket.Chat
- Application type
- Chat & community apps
- Platforms
- Web
- Windows
- macOS
- Linux
- Android
- iOS
Free + paid
Visit site #5 · 58% match
Stoat (formerly Revolt)
- Application type
- Chat & community apps
- Platforms
- Web
- Windows
- macOS
- Linux
- Android
Free
Free
Visit site Slack alternatives compared
Side by side, from the same data used on this page.
| Feature | ||||
|---|---|---|---|---|
| Best for | The one you use now | Closest match | Open source | Free option |
| User rating | ||||
| Pricing | Free + paid | Free + paid | Free + paid | Free + paid |
| Free option | ✓ | ✓ | ✓ | ✓ |
| Open source | ✕ | ✓ | ✓ | ✓ |
| Channels | ✓ | ✓ | — | ✓ |
| Integrations | ✓ | ✓ | — | — |
| Mobile app | ✓ | ✓ | ✓ | ✓ |
| Screen sharing | ✓ | — | — | — |
| Video calls | ✓ | — | ✓ | — |
| Self hosted | — | ✓ | ✓ | ✓ |
| Encrypted | — | — | ✓ | — |
| Voice chat | — | — | ✓ | — |
| Origin | United States | United States | United Kingdom | United States |
| Platforms | Web, Windows, macOS, Linux, Android, iOS | Web, Windows, macOS, Linux, Android, iOS | Web, Windows, macOS, Linux, Android, iOS | Web, Windows, macOS, Linux, Android, iOS |
| Learn more | Get SlackSlack alternatives | Get MattermostMattermost alternatives | Get ElementElement alternatives | Get ZulipZulip alternatives |
✓ confirmed ✕ no — not listed in our data
How we research
- We collect each product's facts from its official website, pricing page and help documentation, and record where we found them.
- Origin, platforms, free options and features are checked against those official sources before an item is listed.
- Software prices are re-checked automatically every day where the pricing page allows it, and every change is logged.
- Rankings come from the data: well-known direct replacements first, then the closest matches by shared features and platforms. Commissions never change the order.
- We only list legal services. Health topics are information only and always point you to a licensed clinician.
- Star ratings come only from reviews by registered users. We never invent ratings or reviews.
Data for Slack last reviewed October 20, 2026. Spotted a mistake? Let us know in the reviews below.
User reviews of Slack
Written by registered users. Ratings on this site come only from these reviews.