This is what I built Jonline for. Haven’t maintained it for a while, but it’s quite functional as-is. Basically a very vanilla Twitter/Reddit-with-first-class-calendar-events, standard Rust web+gRPC server on Postgres DB, React web UI, and no encryption other than HTTPS/TLS. No server-to-server communication, just username/password auth. Super easy to understand APIs (https://jonline.io/docs). (I do need to build better cross-server auth, but this can be done in the FE only with the existing APIs.) Can boot it in a Docker container in seconds. A few “demo” instances I run are linked from the Readme: https://github.com/JonLatane/jonline