A browser-compatibility reference that shows which HTML, CSS, JavaScript, and web platform features are supported across modern browsers.

W3C's online validator for checking CSS syntax and identifying errors against CSS standards.

A concise visual reference for CSS Flexbox properties, helping developers quickly understand and remember layout and alignment techniques.

A visual reference covering CSS Grid properties and layout concepts, designed for quickly looking up grid syntax and positioning techniques.

A collection of pure CSS loading animations and spinners that developers can study, customize, and integrate into web interfaces.

W3C's online service for validating HTML and markup against web standards and identifying syntax or structural errors.

The official learning and reference material for React, explaining components, state, events, hooks, rendering, and modern patterns for building user interfaces.

The international standards organization responsible for developing open web standards and technical specifications for the World Wide Web.

Practical guides and documentation from Google covering modern web development, including HTML, CSS, JavaScript, performance, accessibility, and best practices for building websites.