Developer Tools
JSON, JWT, regex, cron, hashing, formatting — the daily-work toolbox.
30 tools · all run in your browser
Everything a working developer opens in a new tab a dozen times a week: format or minify JSON, decode a JWT to see its payload, hash a file to fingerprint it, build a cron expression without googling the syntax, test a regex against real text, translate a curl command into fetch. All run locally — pasted tokens, config files, and API secrets stay on your device.
The tools cross-link: chainable ones (JSON Formatter, JWT Decoder, Hash Generator, Base64, URL Encoder, and 30+ more) can be piped through the /chains/ route, so you can format JSON, base64-encode it, then hash it in one URL-shareable pipeline. Every tool syncs its state to the URL, so a filled-in tool is a link.
Nothing here needs an install, a signup, or an internet connection after first visit (the site is a PWA — install it and every tool works offline).
All developer tools
- .env File ParserParse a .env file and see it as a JSON object. Handles comments, quoted values, escape sequences, and "export" prefixes. Runs entirely in your browser.
- Base ConverterConvert numbers between binary, octal, decimal, and hexadecimal. Supports huge numbers via BigInt. Handles 0b, 0o, 0x prefixes.
- Credit Card ValidatorValidate credit card numbers with the Luhn algorithm and detect the brand: Visa, Mastercard, American Express, Discover, JCB, Diners Club, UnionPay, and Maestro. Runs entirely in your browser.
- Cron BuilderPick a preset or enter your own fields to build a cron expression. Includes a plain-English explainer so you know exactly when it will run.
- CSS Beautifier & MinifierBeautify minified CSS with proper indentation, or minify pretty CSS to a single line. Preserves comments. Runs in your browser.
- CSV ValidatorPaste any CSV to check for column-count mismatches, unclosed quotes, and delimiter issues. Auto-detects comma/tab/semicolon/pipe and header row. RFC 4180 quoting.
- cURL to fetch() ConverterPaste a curl command and get a JavaScript fetch() equivalent. Handles method, headers, JSON and form bodies, and HTTP Basic auth (-u). Great for copying API docs into code.
- Hash GeneratorInstantly compute MD5 and SHA-family hashes of any text. All hashing happens in your browser — nothing is uploaded, nothing logged.
- HTML Beautifier & MinifierBeautify minified HTML with proper indentation, or minify pretty HTML for production. Preserves script, style, and pre blocks. Runs in your browser.
- HTTP Headers ReferenceEvery common HTTP header explained, grouped by purpose. Searchable by name or keyword. Includes examples and RFC 9110 references.
- HTTP Status CodesEvery HTTP status code you need to know, grouped by category, with plain-English descriptions. Searchable by code, name, or keyword.
- IBAN ValidatorValidate International Bank Account Numbers (IBAN) using the ISO 13616 mod-97 checksum. Detects country, checks expected length, and formats in standard 4-digit groups.
- JSON DiffCompare two JSON documents and see added, removed, and changed keys with dot-path notation. Ignores key order and whitespace. Runs entirely in your browser.
- JSON FormatterFormat, validate, and minify JSON in your browser. See parse errors with line/column. Optional key sorting. Nothing is uploaded.
- JSON String EscapeEscape any text for safe embedding as a JSON string, or unescape a JSON string back to plain text. Handles quotes, backslashes, tabs, and unicode.
- JSON to TypeScriptPaste a JSON blob and get TypeScript interface declarations. Handles nested objects, arrays, and union types. Runs in your browser.
- JWT DecoderPaste any JSON Web Token (JWT) to see the decoded header, payload, and expiration status. Everything happens in your browser — the token never leaves your device.
- NRIC / FIN Generator & ValidatorGenerate structurally valid Singapore NRIC and FIN numbers for test data. Supports S, T, F, G, and M prefixes with correct checksum. Also validates any existing IC number.
- Password GeneratorGenerate strong random passwords with configurable length, character sets, and ambiguity-avoidance. Live entropy meter shows crack time.
- Playwright / Cypress Test GeneratorBuild end-to-end test scripts visually. Add steps — navigate, click, fill, assert — and get ready-to-run Playwright (TypeScript) or Cypress test code instantly. No coding required.
- Random Number GeneratorGenerate random numbers in any range. Integers or decimals, unique or with repeats, Math.random or Web Crypto for cryptographic randomness.
- Regex ExplainerPaste any regular expression and get a token-by-token explanation: anchors, groups, quantifiers, character classes, and escapes. Complements our regex tester.
- Regex TesterTest JavaScript regular expressions against any string with live match highlighting, capture groups (named and numbered), and optional replace.
- Roman Numeral ConverterConvert any number (1–3999) to Roman numerals and back. Validates canonical form and suggests corrections for non-canonical input.
- SQL FormatterFormat and beautify SQL for 10 dialects including PostgreSQL, MySQL, SQLite, BigQuery, Snowflake, and T-SQL. Uppercase keywords, custom indent.
- String Escape / UnescapeEscape and unescape strings for five formats: JSON, JavaScript, HTML, URI components, and SQL literals. Fast, browser-only, safe for copy-paste.
- UEN Generator & ValidatorGenerate structurally valid Singapore UEN (Unique Entity Number) for test data. Supports company (10-char) and business (9-char) formats with checksum. Also validates existing UENs.
- UUID GeneratorGenerate cryptographically-strong UUIDs in bulk. Supports v4 (random), v7 (time-ordered), and the nil UUID. Formatting options included.
- XML FormatterFormat XML with proper indentation, validate against the XML spec, or minify to a single line. Uses the browser DOMParser for validation.
- YAML FormatterFormat and validate YAML in your browser. Multi-document (---) supported. Errors point to line and column. YAML 1.2 spec.
Frequently asked
JSON is a strict, machine-first data format used by APIs. YAML is a superset that supports comments, anchors, and human-friendly indentation — used for config files (Docker Compose, GitHub Actions, Kubernetes). Our JSON ↔ YAML Converter round-trips between them.
No. Base64 is trivially reversible — anyone can decode it in a second. Never use it to hide secrets. Use encryption for secrecy or hashing (SHA-256+) for integrity.
Use a cryptographically secure random source (which is what our Password Generator uses via the browser Web Crypto API), 16+ characters, all four character classes, and no dictionary words. The tool shows a live entropy meter — aim for 80+ bits.
v7 for anything you insert into a database. v7 UUIDs prepend a millisecond timestamp so they sort chronologically, which prevents index fragmentation. v4 is fully random and unordered — fine for tokens, worse for primary keys.
Paste your pattern into our Regex Tester. It runs the browser's native RegExp against your test string, highlights matches, and shows named + numbered capture groups. The g flag is always on so all matches show.
Paste the curl into our cURL to fetch() Converter. Method, headers, JSON/form bodies, and Basic auth (-u) all map to the equivalent fetch() call. Works with multi-line curl commands from API docs.