codecrafters-io/build-your-own-x

This is a curated collection of step-by-step tutorials for re-creating well-known technologies from scratch. Instead of just learning by reading, the project follows the philosophy expressed in its opening Feynman quote: you understand something best when you build it yourself. The repository organizes these tutorials by category, covering things like 3D renderers, BitTorrent clients, blockchains, databases, Docker, emulators, front-end frameworks, games, Git, neural networks, operating systems, programming languages, regex engines, search engines, shells, text editors, web browsers, and web servers, among many others.

The way it works is straightforward: it is essentially an awesome-list, meaning a long, organized index of links pointing out to external articles, videos, books, and code repositories. Each entry is tagged with the language used in that particular tutorial, so a learner can pick a topic they are curious about and a language they want to practice in, then follow that external guide. The repository itself does not contain the tutorial content — it is a directory of resources contributed and maintained by the community.

Someone would use this when they want to deepen their understanding of how a given technology actually works under the hood, when preparing for technical interviews, when looking for a structured side project, or when teaching themselves a new programming language by re-implementing something familiar. The repository itself is written in Markdown, since its job is to present the curated list of links rather than to provide working code. The full README is longer than what was provided.