Jitsi - Open-source and self-hosted video conference platform. You can even try it directly on their website.

IPFS - A distributed file sharing technology which is wonderful for file or site hosting (edit: wether it is uncensorable is open for debate)

Rust - A programming language and a powerful compiler that creates compiled memory-safe programs and can be used nearly everywhere

Fedora + KDE - A combination of a stable modern OS and a complete desktop environment

Wine - launch Windows programs on the latter

Lemmy

Bonus : AlternativeTo to find good open-source alternative software