Mattermost
Slack-style team chat with channels, threads and integrations.
SaaS: Yes, with conditionsClosed product: No
- GitHub stars
- 39.2k
- Deployment
- Docker, Helm, Operator
- Login/SSO
- GitLab OAuth (Team); OIDC/SAML (Enterprise)
Open-source alternatives to Slack
Slack by Salesforce in the Communication category. These are the open alternatives we recommend looking at.
Rocket.Chat
Team and customer chat with federation.
SaaS: YesClosed product: Yes
- GitHub stars
- 46.2k
- Deployment
- Docker, Helm
- Login/SSO
- OAuth/OIDC, SAML, LDAP (some EE)
Zulip
Team chat organised into topic threads.
Apache-2.0Permissive
SaaS: YesClosed product: Yes
- GitHub stars
- 26.0k
- Deployment
- Docker, Installer
- Login/SSO
- SAML, OIDC, LDAP
Element / Synapse (Matrix)
Federated, encrypted chat on the Matrix protocol; used by European public sector.
AGPL-3.0Network copyleft (AGPL)
SaaS: Yes, with conditionsClosed product: No
- GitHub stars
- 4.7k
- Deployment
- Docker, Helm
- Login/SSO
- OIDC, SAML
This is guidance, not legal advice (inte juridisk rådgivning). Check with a lawyer before deciding.
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