Free Frontend Developer Tools — Online Utilities for Everyday CSS
The small tools that save big time. Converters, calculators, checkers — collected in one place, free, with no login required.
Base64 Encoder / Decoder
Encode or decode Base64 — text, JSON, JWTs, and files up to 5 MB. Standard and URL-safe variants with full UTF-8 support and live preview.
Colour Contrast Checker
Check WCAG 2.1 contrast ratios between any two colours — instant AA / AAA pass-fail with a live preview.
CSS Minifier
Paste any CSS and instantly get a minified, production-ready version — strips comments, whitespace, and redundant tokens with live size savings.
CSS Specificity Calculator
Paste any CSS selector and get its (a, b, c) specificity score — with a colour-coded breakdown of every ID, class, attribute, pseudo, and element.
CSS to Tailwind Converter
Paste any CSS and instantly get the Tailwind CSS class equivalents — supports 400+ properties with arbitrary value fallback.
CSS Unit Converter
Convert between every CSS unit — px, rem, em, pt, vw, vh, %, cm, in, deg, rad, ms, dpi — with live context controls and copy-on-click.
CSS Variable Inspector
Paste any :root block and instantly see every --variable as a swatch, chip, or chain — with live filter, type detection, and var() resolution.
HTML Entity Encoder / Decoder
Encode or decode HTML entities — escape <, >, &, quotes, and special characters with named, decimal, or hex output.
PX to REM Converter
Convert pixel values to REM units instantly — set your base font size and get exact REM equivalents.
Responsive Breakpoint Tester
Preview any URL across iPhone, iPad, laptop, and desktop sizes — with Tailwind breakpoint detection, rotation, and live zoom.
Viewport Unit Calculator
Convert pixels to vw, vh, vmin, vmax — and back — at any viewport size, with device presets and a fluid-typography reference table.