The canonical reference for HTML, CSS and JavaScript. If a web platform question has a definitive answer, it lives here — including browser compatibility tables that settle "can I use this?" debates.

The official React documentation, rewritten around hooks and server components. The "Think in React" section is still the clearest introduction to the framework’s mental model.

The best free book-length documentation in software. Ownership and borrowing are explained well enough that the borrow checker starts making sense before chapter 5.

Deeply technical, exhaustively complete, and surprisingly readable for a reference. The EXPLAIN and index chapters are required reading before touching query performance.

A masterclass in small, correct, boring software. The "How To Corrupt An SQLite Database File" page alone is worth the visit for anyone who stores data.

The official Python reference, with a tutorial that is still the fastest way to learn the language properly. The standard library docs are the model for API documentation.

An interactive game that teaches git visually. It finally makes rebase, cherry-pick and reflog concrete instead of abstract commands to memorize.

A modern, well-ordered JavaScript tutorial that covers both the language and the browser APIs, with honest "don’t do this" warnings you rarely get from blogs.

Google’s engineering-focused site for performance and accessibility. The Core Web Vitals explainers are the practical counterpart to the theory.

A comic-book explanation of TLS that is short enough to finish in one sitting and accurate enough that engineers still recommend it to juniors.