MDN Web Docs

The definitive open-source documentation platform for web technologies, maintained by a global community of developers and Mozilla since 2005. Provides exhaustive reference materials, tutorials, and guides covering HTML, CSS, JavaScript, Web APIs, HTTP, and browser extensions. Features include interactive code examples, browser compatibility tables for every CSS property and JavaScript method, detailed specifications with practical usage notes, and a structured learning area for beginners. The platform hosts over 44,000 documentation pages spanning everything from basic HTML elements like forms and tables to advanced JavaScript topics such as async iterators, proxy objects, and Web Workers. Developers rely on it daily for API references including the DOM, Fetch, Canvas, WebGL, Service Workers, and Intersection Observer. The CSS section documents every property, selector, at-rule, and function with live examples, covering modern features like container queries, cascade layers, nesting, anchor positioning, and view transitions. The JavaScript reference covers all built-in objects, statements, operators, and the complete standard library. Each page includes real-world code samples, specification links, and interactive playgrounds. The platform also serves as the canonical reference for Web Standards, documenting emerging specifications before they ship in browsers. With versions available in over 30 languages and a transparent GitHub-based editing workflow, it has become the single most cited resource in web development education and professional work alike.