Build and understand HTTP Cache-Control directives.

Check WCAG text contrast ratios for two web colors.

Convert and preview HEX, RGB, and HSL colors.

Build layered CSS box shadows with a live preview.

Build fluid CSS clamp() values from size and viewport endpoints.

Create copyable linear and radial CSS gradients with a live preview.

Convert relative CSS units with the context that determines their real size.

Inspect an HTML heading outline and spot skipped levels.

Convert text to and from HTML entities directly in your browser.

Parse and inspect raw HTTP header fields locally.

Build encoded URL query strings from key-value parameters.

Convert URL text to and from percent encoding.

Inspect URL components and query parameters.