There's a backend written in Python (in //app/backend), and a web frontend written in TypeScript with React (in //app/web).
The web frontend is a static app that we deploy on a CDN (AWS CloudFront through an S3 bucket). The web frontend talks to the backend through gRPC, a Remote Procedure Call library that uses Protocol Buffers, or protobufs (in //app/proto). gRPC uses HTTP/2 framing but is not fully compatible with the web HTTP/2 so we use gRPC-Web that works with any version of HTTP along with a proxy that translates the two when using these in the browser. For that there's Envoy proxy (in //app/proxy). Additionally the deployed version has an nginx reverse proxy for TLS termination (in //app/nginx).
User media is uploaded to the media server (in //app/media). It's built into a different container and will eventually run on a different machine. The purpose is to isolate user content (which can potentially be arbitrary user content) from the main server. It's also served off a different domain for cookie protection and CSP reasons.
Everything's built into docker containers and can be spun up together with docker-compose. This gives us an easy way to deploy the app, as well as some isolation and reproducibility afforded by containerisation.
The //app/deployment folder contains code for deploying the app. The app is literally composed of stuff in this repo and a few config files (with API keys, etc) dropped in //app. //app/deployment/deps.sh should basically install all dependencies. You'd need to tweak the nginx container though and rebuild the containers if you wanted to deploy on a different domain.