MDN Web Docs

What it is

MDN is the documentation for the web platform itself. It is owned by Mozilla and written with a global community of volunteers and partners, including Open Web Docs, Google, Microsoft, W3C and Igalia. Every HTML element, CSS property, JavaScript feature and Web API has a page with a description, syntax, runnable examples, links to the specification and a compatibility table. According to MDN's own About page (September 2026), the site has about 45,000 pages in 7 languages and more than 15 million users a month.

Why it should be your default reference

Search results for web questions are full of tutorials of unknown age, and the web platform keeps changing. MDN pages describe specified behaviour, and the compatibility tables come from the browser-compat-data project, which also powers tools like Can I Use. That means you learn what is true now, not what was true when a blog post was written. Most bootcamps, universities and learning platforms point students to MDN for the same reason.

The parts people overlook

• The Learn area: a structured beginner curriculum for HTML, CSS and JavaScript, with guides, assessments and, through a partnership with Scrimba, some interactive courses. Many people only ever land on reference pages and never notice it.
• Guides, not just reference: long-form guides on topics like CSS layout, the Fetch API, JavaScript modules and HTTP caching are among the best free explanations available.
• Tools: a code Playground and the HTTP Observatory, which scans a site's security headers.

How to use it well

• Add mdn to your search queries, or set MDN as a custom search shortcut in your browser.
• Always check the compatibility table before using a newer feature in production.
• Read the examples, then change them in the Playground. Small experiments teach faster than rereading.
• When a tutorial and MDN disagree, trust MDN and look at the specification link if you need the final word.

Free versus MDN Plus

All documentation is free with no account. MDN Plus is an optional paid subscription with extras such as AI-powered help and saved collections. None of the core learning or reference content is behind it, so most learners never need it.

Common questions

Is MDN good for complete beginners? Yes, through the Learn area. It is thorough and accurate, though drier than video courses, so some beginners pair it with a more guided course.

MDN or W3Schools? W3Schools is quicker for a one-line reminder. MDN is more accurate and complete, explains edge cases and browser support, and is the better habit to build.

Can I contribute? Yes. The content lives on GitHub (mdn/content had about 11k stars in September 2026), and fixing a typo or example is a common first open source contribution.

Best for: every web developer, at every level, permanently.