Runtime Lab — Learn Backend & Systems Engineering by building real software from scratch

Hey everyone, With the heavy shift toward AI codegen tools, I realized a lot of us (myself included) are starting to lose touch with core, low-level engineering fundamentals. If an API or LLM service drops, are we still confident in our core mechanics? To fix this for myself, I created Runtime Lab (runtimelab.io)— an interactive, browser-based environment for building fundamental systems from scratch with zero installation required . Instead of building another basic web app, the challenges focus on low-level systems: Building your own custom Postgres driver Writing an in-memory job queue Building custom memory/kernel allocators Creating Redis clones and HTTP parsers Everything runs in 4 main languages (Go, Python, C, C++) across 17+ live challenges. It's completely free to check out. I'd love to get feedback from engineers here on what low-level topics or languages you'd like to see covered next! runtimelab.io