Mattermost
Mattermost provides a flexible, open-source platform for secure team collaboration, designed for organizations with strict security and privacy requirements.
Open Source Alternative to:
Similar projects
More open source repositories worth checking out.
build-your-own-x
Open to contributorsOpen
Master programming by recreating your favorite technologies from scratch.
21/02/2026
47,895
504,878
awesome
Open to contributorsOpen
😎 Awesome lists about all kinds of interesting topics
05/05/2026
35,175
470,254
freeCodeCamp
Open to contributorsOpen
freeCodeCamp.org's open-source codebase and curriculum. Learn math, programming, and computer science for free.
26/05/2026
44,698
445,418
public-apis
Open to contributorsOpen
A collective list of free APIs
26/05/2026
47,936
437,277