I'm a beginner programmer, and a common suggestion here on HN is to look at high-quality, open-source codebases, as a technique to write better code and for inspiration.
Please post links below, and if possible, why you like it so much!
I work as a robotics researcher and code primarily in C++ and Python, but feel free to link projects outside these languages as well.
Thanks!
https://github.com/TheThingsNetwork/lorawan-stack (nice docs + contribution process)
https://github.com/cli/cli (well made cli, awesome --help & flag conventions)
https://github.com/denoland/deno_website2 (next.js codebase with serverless cloudflare workers being used)
Mostly as it uses tech I like using already.
On top of that I have Elasticsearch/Kibana allowing me to build up my own little private search engine.
Redis.