Free Online Web Developer Tools
The everyday utilities of a web developer
Web development is full of small transformations and lookups that break flow when you have to hunt for a page each time. Converting a HEX to HSL for a stylesheet, generating a CSS gradient for a hero background, parsing a User-Agent string from a bug report, or checking the exact meaning of a 422 vs 409 status code — these tasks add up over a week. This category bundles those utilities into fast, dedicated pages that ship with documentation and copy-paste snippets, so you can get in, get the answer, and get back to shipping.
All Web Developer Tools
cURL Converter
Convert cURL commands to Python (requests), JavaScript (fetch), Node.js, Go (net/http), PHP, or Java (HttpClient). Parses -H, -d, --data-urlencode, -F, -u, --json and more. 100% local.
URL Parser
Parse any URL into scheme, host, port, path, and query parameters — or build a URL from scratch with a form. Great for debugging redirect chains, tracking pixels, and OAuth flows. 100% local.
CIDR Calculator
Calculate IPv4 subnets from CIDR notation online. Get network address, broadcast, netmask, wildcard, usable host range, IP class, and binary representation. 100% local — nothing leaves your browser.
Color Converter
Convert colors between HEX, RGB, HSL, and HSV instantly with a live color preview and copy-ready CSS strings. Free, no signup, runs entirely in your browser.
Meta Tag Preview
Preview how your page will appear in Google search results and social share cards on Facebook, Twitter/X, and LinkedIn. Parses <title>, meta description, canonical, and full Open Graph / Twitter Card tags with diagnostics. 100% local.
HTML Minifier
Minify HTML by removing comments, collapsing whitespace, and stripping optional attribute quotes and void-element slashes. Reports byte savings. Preserves IE conditional comments and preformatted <pre> / <textarea> / <script> / <style> content. 100% local.
HTML Beautify
Format messy or minified HTML with clean indentation and line breaks. Handles void elements (<br />), preserves preformatted <pre> / <textarea> / <script> / <style>, and normalizes self-closing tags. 100% local.
User Agent Parser
Parse User-Agent strings to identify browser, engine, operating system, and device. Instantly see what your own browser sends.
HTTP Status Codes
Complete reference of HTTP status codes with meanings, use cases, and RFC citations. Search 60+ codes from 100 Continue to 511 Network Authentication Required.
CSS Gradient
Design linear, radial, and conic CSS gradients with a visual color-stop editor. Copy production-ready CSS or Tailwind classes. Free, no signup, runs entirely in your browser.
Box Shadow
Design CSS box-shadow interactively with live preview. Multiple layers (Material-style elevation, neumorphic, inset shadows), presets, and one-click copy. 100% local.
Border Radius
Round any HTML element with an intuitive per-corner editor. Supports px / % units and elliptical corners (border-radius: 10px 20px / 5px 15px) for organic blob shapes. 100% local.
cubic-bezier
Design custom cubic-bezier() easing functions with two draggable control handles. Live animation preview, common presets (ease, back-out, etc.), and copy-ready CSS. 100% local.
Text Shadow
Design CSS text-shadow effects with layered offsets, blur, and color. Presets for neon glow, retro double-stroke, emboss, and soft drop shadow. Live preview at your chosen font size. 100% local.
Glassmorphism
Design frosted-glass CSS effects (glassmorphism) — semi-transparent background + backdrop-filter blur + subtle border and shadow. Live preview on a colorful gradient, copy production-ready CSS with Safari prefix. 100% local.
Flexbox Generator
Interactive CSS flexbox generator. Adjust flex-direction, justify-content, align-items, gap, wrap and per-item grow/shrink/basis/order with live preview. Copy production-ready CSS or Tailwind classes. 100% local.
Grid Generator
Interactive CSS Grid playground. Configure grid-template-columns / rows with fr / px / auto tracks, gap, and per-item span. Live preview + copy-ready CSS and Tailwind classes. 100% local.
XML Validator
Validate XML syntax online. Paste your XML and get instant pass/fail with the exact error location. Uses the browser's DOMParser — runs 100% locally, no server needed.
Email Validator
Validate email addresses for correct syntax. Batch-check multiple addresses at once — paste one per line. Checks local part, domain, TLD, and length limits. Runs locally, no data sent anywhere.
Regex Visualizer
Test and explain regular expressions. Paste a pattern and test string — see all matches highlighted with positions, plus a plain-English breakdown of every token in your regex. 100% local.
CSS Minifier
Minify CSS online — strip comments, whitespace, and unnecessary characters. See exact bytes saved. Output is valid CSS. 100% local, no upload.
Contrast Checker
Check color contrast between text and background colors. Shows WCAG AA and AAA compliance (normal and large text). Instant visual preview with the color pair. Free, no signup.
JS Minifier
Minify JavaScript online — remove comments, whitespace, and newlines. See byte savings. For production-grade minification (dead code, variable renaming), use Terser or esbuild. 100% local.
Robots.txt Generator
Generate a robots.txt file for your website. Configure user-agent, allow/disallow rules, and sitemap URL. Perfect for SEO — controls how search engines crawl your site. Free, no signup.
UTM Builder
Build UTM-tagged campaign URLs for Google Analytics. Set utm_source, utm_medium, utm_campaign, utm_term, and utm_content. Copy the complete tagged URL in one click. 100% local.
Meta Tag Generator
Generate meta tags for your website — title, description, Open Graph (Facebook/LinkedIn), Twitter Card, favicon, and viewport. Copy the complete HTML snippet to paste into your <head> section. 100% local.
HTML Preview
Write HTML and see the live rendered result instantly. Side-by-side editor and preview pane. Perfect for testing snippets, email templates, and quick prototypes. 100% local.
Chmod Calculator
Calculate Unix file permissions with an interactive chmod calculator. Toggle read/write/execute for Owner, Group, and Others. Shows numeric (755, 644) and symbolic (rwx) output. Free, no signup.
Cookie Parser
Parse cookie strings from HTTP headers or document.cookie into readable key-value pairs. Handles URI-encoded values. 100% local.
Bulk URL Opener
Paste a list of URLs and open them all with one click. Each URL opens in a new tab. For checking links, opening bookmarks, or batch-testing endpoints. 100% local.
CSS Specificity
Calculate CSS selector specificity. See exactly how each part of a selector contributes to the (a,b,c,d) weight. Includes IDs, classes, attributes, pseudo-classes, type selectors, and pseudo-elements. 100% local.
Email Header Analyzer
Parse raw email headers into a structured table. See From, To, Subject, Date, Return-Path, SPF, DKIM, DMARC, Authentication-Results, and the full Received chain. Perfect for debugging email delivery and spoofing. 100% local.
When to use these tools
Use these tools when tweaking design tokens, building a landing page background, investigating an unusual browser in your logs, or picking the semantically correct HTTP status code for an API response.
Frequently Asked Questions
Are the CSS outputs production-ready?
Yes. Generated CSS uses standard syntax that works in all modern browsers without vendor prefixes. For older browser support, add a solid `background-color` fallback in your stylesheet.
Can I rely on User-Agent parsing for feature detection?
No. UA strings can be spoofed and are being deliberately reduced by Chromium. Use feature detection in your code and reserve UA parsing for analytics or support debugging.