51 free tools
Developer tools
The small utilities you reach for ten times a day: format and validate JSON, test regular expressions, decode JWTs, encode and decode Base64, URLs, and HTML entities, convert between CSV and JSON, explain cron expressions, generate UUIDs and hashes, and minify CSS or JavaScript.
All developer tools
ASCII Converter
ASCII converter that turns text into decimal, hex, binary, or octal character codes and back, live as you type. Unicode and emoji safe. Free.
Aspect Ratio Calculator
Aspect ratio calculator that simplifies width and height to a ratio like 16:9 and finds the missing dimension for a resize. Presets for video and social.
Base64 Encoder Decoder
Base64 encoder and decoder that converts text to Base64 and back in your browser. Handles UTF-8, emoji, Base64URL, and files. Free, no uploads.
Binary Decimal Converter
Binary to decimal converter that also handles hex and octal. Type in any box and the others update, with exact results for very large numbers.
Border Radius Generator
Set each corner's CSS border-radius in px, % or rem, including elliptical 8-value blob shapes. Live preview, presets and the shortest shorthand to copy.
Box Shadow Generator
Design CSS box shadows with multiple layers, inset, spread and opacity. Live preview, presets for soft, card, glow and neumorphic styles, copy-ready CSS.
Chmod Calculator
Convert Linux file permissions between octal (755), symbolic (rwxr-xr-x) and checkboxes. Includes setuid, setgid, sticky bit and ready chmod commands.
Click Speed Test
Test your clicks per second with 1, 5, 10 and 30 second CPS tests. Works with mouse, touch or keyboard, and saves your personal bests in your browser.
Color Contrast Checker
Color contrast checker that tests text and background colors against WCAG 2.2 AA and AAA. Get the contrast ratio, pass/fail, and a live preview.
Color Converter
HEX to RGB converter that also outputs HSL, HSV, and CMYK. Paste a HEX code, rgb(), hsl(), or CSS color name and copy any format in one click.
Color Palette Generator
Color palette generator that builds a 50-900 shade scale plus complementary, analogous, triadic, and tetradic palettes from one base color. Copy CSS.
Cron Expression Explainer
Cron expression explainer that translates crontab schedules into plain English and lists the next 5 run times. Supports ranges, steps, names, and @daily.
Cron Expression Generator
Build a cron expression from simple dropdowns, see it in plain English, and preview the next 5 run times. For crontab, GitHub Actions, and Kubernetes.
CSS Clamp Calculator
CSS clamp() calculator for fluid font sizes and spacing. Enter min and max sizes and viewports to get a rem-based clamp() value you can copy.
CSS Gradient Generator
Build linear, radial and conic CSS gradients with unlimited color stops and a live preview. Presets, repeating stripes and copy-ready CSS with a fallback.
CSS Minifier
CSS minifier that strips comments and whitespace as you type, keeps strings and selectors intact, and shows bytes saved. Free, runs in your browser.
CSV JSON Converter
CSV to JSON converter that handles quoted commas, tabs from Excel, and number types. Copy or download the JSON instantly. Nothing is uploaded.
CSV Table Generator
Markdown table generator: paste CSV or cells from Excel and Google Sheets, pick column alignment, and copy a clean GitHub-ready table.
CSV to SQL Converter
Turn CSV into SQL CREATE TABLE and INSERT statements for PostgreSQL, MySQL, SQLite or SQL Server, with type inference and safe escaping. Runs in-browser.
DNS Lookup Helper
DNS lookup helper that writes ready-to-run dig, nslookup, host, and PowerShell commands for A, MX, TXT, CNAME, NS, CAA, and PTR records.
Favicon Generator
Make a favicon from text, emoji or an image. Get favicon.ico, PNGs from 16 to 512px, an apple-touch-icon, manifest and HTML tags in one zip. No upload.
Hash Generator
Hash generator for SHA-256, SHA-512, SHA-384, SHA-1, MD5, and CRC32. Hash text or a file and compare it against a published checksum. Runs locally.
HTML Entity Encoder Decoder
HTML entity encoder and decoder: escape <, >, &, and quotes for safe HTML, or decode &, , and é back to text. Live, with copy.
HTML Formatter
Beautify minified or messy HTML with clean indentation, or minify it. Keeps inline text, pre blocks, and scripts intact. Runs in your browser, no uploads.
HTML Table Generator
HTML table generator: paste CSV or spreadsheet cells and get clean, escaped table code with thead, caption, and optional email-safe inline styles.
HTML to Markdown
Convert HTML or rich text from Google Docs, Word and web pages to clean Markdown. Tables, nested lists, code and links handled. Runs in your browser.
HTML Viewer
Paste HTML, CSS, and JavaScript and see a live preview in a secure sandbox. Test desktop, tablet, and mobile widths. Nothing is uploaded or stored.
HTTP Status Code Lookup
HTTP status code lookup: search 50+ codes from 100 to 511, plus Cloudflare 52x, with plain-English meanings and SEO notes for redirects and errors.
IP Subnet Calculator
Subnet calculator for IPv4. Enter an IP with a CIDR prefix or subnet mask to get the network, broadcast, usable host range, and wildcard mask.
JavaScript Minifier
JavaScript minifier that strips comments and whitespace without breaking strings, regex, or template literals. ASI-safe, instant, and 100% local.
JSON CSV Converter
JSON to CSV converter that flattens nested objects, escapes commas and quotes, and downloads an Excel-ready file. Runs locally; nothing uploaded.
JSON Formatter
JSON formatter and validator that runs 100% in your browser. Beautify, minify, sort keys, and find errors by line. Nothing is uploaded or saved.
JSON String Escape
JSON string escape and unescape tool for quotes, backslashes, newlines, tabs, and Unicode. Paste text, get a valid JSON string instantly, fully offline.
JSON to TypeScript
Convert JSON to TypeScript interfaces or types. Nested objects, merged array types and optional fields detected automatically. Runs in your browser.
Markdown Previewer
Markdown previewer with live side-by-side rendering of headings, lists, task lists, tables, code blocks, and links. Copy the HTML. Runs offline.
Mic Test
Test your microphone online with a live level meter and waveform. Pick a device, spot clipping, and fix permission errors. Nothing is recorded or uploaded.
Reaction Time Test
Test your reaction time: wait for green, click, and get your time in milliseconds. Five-round averages, personal bests and history saved in your browser.
Redirect Generator
301 redirect generator: turn old and new URL pairs into ready-to-paste rules for Apache .htaccess, Nginx, Netlify, Cloudflare Pages, and Vercel.
Regex Tester
Regex tester for JavaScript: highlight matches live, inspect capture groups and named groups, try find-and-replace, and see clear error messages.
REM PX Converter
REM to PX converter: type pixels or rem and get the other instantly at any root font size, plus a px-to-rem chart of common CSS sizes.
Robots.txt Generator
Robots.txt generator: build a valid file with disallow and allow rules, sitemap links, and optional AI crawler blocking. Copy or download instantly.
Screen PPI Calculator
PPI calculator for monitors, laptops, phones, and TVs: get pixel density, dot pitch, aspect ratio, physical size, and the distance where pixels disappear.
Sitemap URL Generator
Sitemap URL generator: turn a list of paths into a valid XML sitemap or clean absolute URL list. Removes duplicates, adds lastmod, and escapes characters.
Spacebar Counter
Spacebar counter: see how many times you can hit the space bar in 5, 10, 30 or 60 seconds, or with no limit. Presses per second and best scores saved.
SQL Formatter
Format and beautify SQL for PostgreSQL, MySQL, SQL Server, BigQuery, Snowflake, and more. Minify too. Runs in your browser, so queries never leave it.
Timestamp Converter
Timestamp converter for Unix epoch seconds or milliseconds (auto-detected). See local time, UTC ISO 8601, and time ago, or convert a date back.
URL Encoder Decoder
URL encoder and decoder: percent-encode query values or decode %20-style text instantly. Uses encodeURIComponent with full UTF-8 support.
URL Parser
URL parser that breaks any link into protocol, host, port, path, hash, and decoded query parameters, using your browser's own URL engine.
UUID Generator
UUID generator for random v4 UUIDs: create 1 to 500 at once with crypto-grade randomness, uppercase or no-hyphen options, and copy all.
XML Formatter
Pretty print, minify, and check XML for well-formedness with exact line and column errors. Uses your browser's own parser, so nothing is uploaded.
YAML to JSON Converter
Convert YAML to JSON and JSON to YAML live, with validation errors that show the exact line and column. Kubernetes-ready. Runs fully in your browser.
About these tools
Every tool runs on the browser's own engine. The JSON formatter uses the native parser, so if it formats, it is valid. The regex tester uses JavaScript's RegExp, so matches behave the way they will in your frontend code. Hashes come from the Web Crypto API.
That also means nothing you paste is sent to a server. API responses, access tokens, and customer records stay on your machine, which is the main reason to prefer a client-side tool over a random online formatter when you are debugging production data. Still, rotate any secret you paste anywhere you do not control.