suitenumerique/docs. New open source (MIT licensed) collaborative text editing web application, similar to Google Docs or Notion, notable because it's a joint effort funded by the French and German governments and "currently onboarding the Netherlands".
It's built using Django and React:
Docs is built on top of Django Rest Framework, Next.js, BlockNote.js, HocusPocus and Yjs.
Deployments currently require Kubernetes, PostgreSQL, memcached, an S3 bucket (or compatible) and an OIDC provider.