21 developer tools, and counting

Free Developer Tools — JSON, JWT, Hash & Regex

Format JSON and XML, decode JWTs, test regex, generate UUIDs, hashes, passwords and QR codes, convert timestamps and bases — no install, no sign-up.

Runs on your device
No uploads
Free, no sign-up
Works on any device

Most used

Where most people start in developer tools.

All 21

JSON FormatterPretty-print, minify and validate JSON with the exact line and column of any error — formatted instantly in your browser, nothing is uploaded.JWT DecoderDecode a JSON Web Token's header and payload with readable dates and an expiry check — entirely in your browser, so your token never leaves your device.Regex TesterTest regular expressions against sample text with live match highlighting, capture groups and flags — JavaScript flavour, running entirely in your browser.Password GeneratorGenerate strong random passwords with custom length and character options — with a strength meter, created securely in your browser and never sent anywhere.

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QR Code GeneratorCreate QR codes for links, text and Wi-Fi networks — customize size and colors, then download as PNG or SVG, all generated in your browser.Password GeneratorGenerate strong random passwords with custom length and character options — with a strength meter, created securely in your browser and never sent anywhere.UUID GeneratorGenerate random v4 or time-ordered v7 UUIDs — one or up to 100 at a time, with uppercase and no-hyphen options, all created in your browser.Base64 Encoder & DecoderEncode text to Base64 or decode Base64 back to text — UTF-8 safe with a URL-safe option, converted instantly in your browser with nothing uploaded.URL Encoder & DecoderPercent-encode or decode URLs and query strings — encode a single value or a full URL, converted instantly in your browser with nothing uploaded.Hash GeneratorGenerate SHA-256, SHA-512 and SHA-1 hashes of any text at once — computed instantly in your browser with Web Crypto, nothing is uploaded.File Hash CheckerGenerate MD5, SHA-1 and SHA-256 checksums for any file and verify it against a known hash — computed instantly in your browser, nothing is uploaded.JWT DecoderDecode a JSON Web Token's header and payload with readable dates and an expiry check — entirely in your browser, so your token never leaves your device.JSON FormatterPretty-print, minify and validate JSON with the exact line and column of any error — formatted instantly in your browser, nothing is uploaded.Unix Timestamp ConverterConvert Unix timestamps to readable dates and back — seconds or milliseconds auto-detected, with local, UTC and ISO 8601 output, all in your browser.Color ConverterConvert colors between HEX, RGB and HSL with a live swatch and contrast check — paste any format or use the picker, all in your browser.Regex TesterTest regular expressions against sample text with live match highlighting, capture groups and flags — JavaScript flavour, running entirely in your browser.GSTIN ValidatorValidate any GSTIN — checks format, state code, embedded PAN, and the MOD-11 checksum, with a full breakdown of each segment. Bulk validation supported.PAN & Aadhaar ValidatorCheck the format of any PAN (structure + entity type) or Aadhaar (Verhoeff checksum) — a client-side format check, no government database lookup.Cron Expression GeneratorBuild or decode cron expressions visually — edit any field, use @yearly/@daily shortcuts, and see the next 5 scheduled run times, all in your browser.Number Base ConverterConvert numbers between binary, octal, decimal and hexadecimal — type in any base and see all others update live, all in your browser.HTML Encoder & DecoderEncode special characters to HTML entities (&, <, >, &#x…) or decode them back to plain text — instantly in your browser with nothing uploaded.XML FormatterPretty-print and validate XML with the exact line and column of any error — formatted instantly in your browser, nothing is uploaded.JSON DiffCompare two JSON objects and see exactly what changed — added, removed and modified keys highlighted side by side, all in your browser with no upload.HTTP Status CodesA searchable reference for all HTTP status codes — 1xx to 5xx — with name, description and common use cases, all in your browser.CSS / JS MinifierMinify CSS or JavaScript to reduce file size — strip comments, whitespace and shorten identifiers, then copy or download the output, all in your browser with no upload.

What people use these for

Start from the job you need done.

Read an unreadable payloadPretty-print, minify and validate JSON with the exact line and column of any syntax error.JSON Formatter Inspect a tokenDecode a JWT's header and payload with readable dates and an expiry check — locally, so the token stays yours.JWT Decoder Debug a patternTest a regex against sample text with live match highlighting, capture groups and flags.Regex Tester Generate identifiersCreate random v4 or time-ordered v7 UUIDs, one or a hundred at a time.UUID Generator Make a strong passwordGenerate a password with the length and character set you need, checked against a strength meter.Password Generator Decode a timestampConvert Unix seconds or milliseconds to local, UTC and ISO 8601 — and back again.Unix Timestamp Converter

About these developer tools

The utilities you reach for a dozen times a day — pretty-print this JSON, what's inside this token, does this regex match, give me a UUID, what time is 1735689600 — are exactly the ones you shouldn't paste into an unknown website. Tokens and payloads have a habit of containing real credentials.

Everything in this set is computed locally with the browser's own APIs: Web Crypto for hashes and random values, the native JSON and RegExp engines for parsing and matching. Nothing is transmitted, so pasting a production token is no riskier than opening a text editor.

Frequently asked questions

Is it safe to paste a real JWT or API response here?

Yes — decoding and formatting happen entirely in your browser and nothing is logged or sent anywhere. You can confirm it by opening devtools and watching the network tab stay empty, or by disconnecting from the internet first.

Does the JWT decoder verify the signature?

No. It decodes and displays the header and payload and checks the expiry claim. Verifying the signature needs the secret or public key, which belongs on your server, not in a browser tab.

Are the generated passwords and UUIDs actually random?

They come from the Web Crypto API's cryptographically secure random generator, not Math.random(), so they're suitable for real credentials.

Which regex flavour does the tester use?

JavaScript's, since it runs on the browser's native RegExp engine. Most patterns carry over to other languages, but lookbehind and named-group syntax can differ.

Can I hash a file, not just text?

The hash generator works on text input, producing SHA-256, SHA-512 and SHA-1 at once. For file integrity checks, your operating system's built-in checksum command is the better fit.

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