Developer tools
Free developer tools for JSON, JWTs, Base64, cron, timestamps, colors and more. They run in your browser, so nothing you paste leaves the page.
JSON and data10
Format, compare, query and convert structured data.
- JSON Formatter & ValidatorFormat, minify and check JSON, and see the exact line and column where it breaks.
- JSON DiffCompare two JSON documents by path and copy the JSON Patch that turns one into the other.
- JSONPath TesterRun a JSONPath expression over your JSON and see every value it selects, at the path it lives at.
- JSON ↔ YAML ConverterConvert between JSON and YAML: anchors resolved, multi-document files handled, and output that round-trips.
- YAML Validator & FormatterFind the line where YAML breaks, warn about the traps that change what it means, and reformat it with comments kept.
- TOML ↔ JSON ConverterConvert between TOML and JSON: tables, arrays of tables, dotted keys and every value kind, with errors that point.
- CSV ↔ JSON ConverterConvert between CSV and JSON: RFC 4180 quoting, an auto-detected delimiter, typed values, and a preview of the table.
- XML Formatter & ValidatorFormat, minify and check XML, and point at the exact spot where it breaks.
- JSON to TypeScriptTurn a JSON sample into TypeScript interfaces or type aliases, with a Zod schema when you want one.
- JSON to GoTurn a JSON sample into Go structs with json tags, ready to paste into a file.
Tokens, hashes and secrets8
Read and make JWTs, hash and sign, and generate IDs and passwords.
- JWT DecoderDecode a JSON Web Token in your browser and read its header, claims and expiry in plain words.
- JWT EncoderSign a JSON Web Token with HMAC — edit the header and the claims, pick HS256, HS384 or HS512.
- Hash GeneratorHash text with MD5, SHA-1, SHA-256, SHA-384 and SHA-512 at once, and check a hash against it.
- HMAC GeneratorSign a message with a secret key — HMAC over SHA-256, SHA-512, SHA-1 or MD5 — and check a signature against it.
- Password GeneratorMake strong passwords and passphrases from your browser’s own randomness, and check how strong a password is.
- Random String GeneratorDraw random strings, tokens and IDs in your browser: hex, base64url, NanoID, ULID, or an alphabet of your own.
- UUID Generator & DecoderGenerate version 4 and 7 UUIDs, or take any UUID apart: its version, its variant, and when a time-based one was made.
- CSP BuilderBuild a Content-Security-Policy header, or paste one to see what it allows and where it is weak.
Encoding7
Base64, URLs, entities, escapes and the bytes underneath.
- Base64 Encoder & DecoderEncode text to Base64 and decode it back, in the standard or URL-safe alphabet, without your text leaving the page.
- URL Encoder & DecoderPercent-encode text for URLs, decode it back, and take a URL apart into its pieces.
- HTML Entity Encoder & DecoderEscape text into HTML entities and read them back, named where a name exists and numeric otherwise.
- String Escape & UnescapeEscape and unescape strings for JSON, JavaScript, Java, C#, Python, SQL, MySQL, regex, the shell and CSV.
- Text to Binary ConverterConvert text to binary, hex, decimal or octal bytes, and back — UTF-8, UTF-16 or ASCII, without leaving the page.
- ASCII TableEvery ASCII character with its decimal, hex, octal, binary and HTML code, and a lookup for any character.
- QR Code GeneratorMake a QR code for a link, Wi-Fi, an email or a phone number, and download it as SVG or PNG.
Time and dates5
Timestamps, time zones, durations and cron schedules.
- Unix Timestamp ConverterTurn Unix timestamps into dates and back, in any timezone.
- Cron BuilderRead and write cron expressions in plain English, with the next run times in any timezone.
- Time Zone ConverterConvert a date and time between time zones, and see it in several at once.
- Date CalculatorCount the days between two dates, and add or subtract days, weeks, months and years.
- ISO 8601 Duration ConverterRead and write ISO 8601 durations like P1DT2H30M, and convert them to seconds and back.
CSS and color7
Gradients, shadows, units, palettes and tidy stylesheets.
- Color Converter & Contrast CheckerConvert a color between HEX, RGB, HSL and OKLCH, and check two colors against WCAG.
- Color Palette GeneratorPick one color and get its harmonies, a Tailwind-style 50-to-950 scale, contrast ratios and paste-ready CSS.
- CSS Gradient GeneratorBuild linear, radial and conic gradients by eye: drag the color stops, try a preset and copy the CSS.
- Box Shadow GeneratorDesign CSS box shadows layer by layer, preview them, and copy the value with a matching Tailwind class.
- PX to REM ConverterConvert px, rem, em, pt and % in both directions, at any root font size.
- CSS FormatterFormat or minify CSS, with strings, url()s and custom properties kept exactly as written.
- SVG OptimizerStrip editor junk, round coordinates and shorten path data, and see both drawings side by side.
Web and HTTP6
Status codes, MIME types, user agents, robots.txt and curl.
- HTTP Status CodesLook up any HTTP status code: what it means, when to use it, and what clients do with it.
- curl to Code ConverterTurn a curl command into JavaScript, Python, Go or PHP, with the request it builds and every flag left out.
- MIME Type LookupLook up the MIME type for a file extension, or the extensions for a MIME type.
- User Agent ParserRead a User-Agent string: browser, engine, operating system, device, and whether it is a known crawler.
- Robots.txt TesterCheck a robots.txt: would this crawler be allowed to fetch this URL, and which rule decided?
- HTML FormatterFormat or minify HTML, keeping script, style, pre and textarea exactly as written.
Shell, git and servers5
Permissions, subnets, Compose files, ignores and version ranges.
- chmod CalculatorConvert Unix permissions between octal and symbolic notation, special bits included.
- CIDR & Subnet CalculatorWork out what an IPv4 or IPv6 block covers, split it into subnets, and check whether an address is inside it.
- docker run to Compose ConverterTurn docker run commands into a compose.yaml service, and a Compose file back into commands, flag by flag.
- Gitignore GeneratorBuild a .gitignore for your stack, and check whether a path would be ignored.
- Semver Range CheckerCheck which versions satisfy an npm semver range, and read what the range means in plain words.
Numbers and bits3
Bases, bitwise operations and data sizes.
- Number Base ConverterConvert a number between binary, octal, decimal, hex and any base from 2 to 36, however big it is.
- Bitwise CalculatorWork out AND, OR, XOR, NOT and shifts at any width, and see every bit of both operands and the answer.
- Data Size ConverterConvert bits, bytes, kB and MB against KiB, MiB and GiB exactly, and time a download.
Text and regex7
Test regular expressions, change case, count words, compare text and preview Markdown.
- Regex TesterTest a JavaScript regex on your text: every match and group, replace, and the pattern explained in plain English.
- Diff CheckerCompare two texts line by line, word by word or character by character, and copy the unified diff.
- Case ConverterConvert text between camelCase, PascalCase, snake_case, kebab-case, Title Case and more, and make a URL slug.
- Word CounterCount words, characters, sentences and paragraphs as you type, with reading and speaking time.
- Markdown Editor & PreviewWrite Markdown, see it rendered, and copy the HTML.
- Markdown Table GeneratorDraw a table in a grid, or paste CSV, TSV or a spreadsheet selection, and copy clean Markdown back out.
- Lorem Ipsum GeneratorGenerate classic Lorem Ipsum or developer-flavored filler, by the paragraph, sentence or word.
SQL1
Write it, read it, format it.