Creator here. Six Degrees of Wikipedia is a side project I've been sporadically hacking on over the past few years. It was an interesting technical challenge and it's fun to play with the end result. Here's the tech stack:
* Frontend: React (Create React App)
* Backend: Python Flask
* Database: SQLite
* Web (frontend) hosting: Firebase Hosting
* Server (backend) hosting: Google Compute Engine (it runs fine on a tiny f1-micro instance)
All the code is open source[1] and I'm happy to answer any questions about building or maintaining it!
[1] https://github.com/jwngr/sdow