Zulip : Powerful slack-like open source group chat
cal.com : Open source meeting scheduling tool. Send a link, let others book a slot. Calendly alternative.
Keycloak : Keycloak is an Open Source Identity and Access Management solution for modern Applications and Services.
Prometheus : Prometheus is an open-source systems monitoring and alerting toolkit originally built at SoundCloud. Prometheus's main features are:
a multi-dimensio...
GitLab is a web-based Git repository manager with wiki and issue tracking features. GitLab offers hosted accounts similar to GitHub, but also allows its software to be used on third party servers.