Free online developer tools
Format and validate JSON and XML, test JavaScript regular expressions, decode JWTs, build cron expressions, encode Base64, generate hashes, and convert number bases. Payloads and tokens are processed in your browser and are not sent to a server.
Hash GeneratorGenerate SHA-256, SHA-512, SHA-1 and MD5 hashes of any text and check them against an expected checksum. Free, and the text never leaves your browser.Barcode GeneratorCreate Code 128, EAN-13, UPC or QR code labels, check the value fits the format, and download a PNG or SVG to print. Free and made in your browser.Cron GeneratorBuild a cron expression from presets or five fields, read it in plain English, and preview the next run times. Free and works entirely in your browser.JSON FormatterFormat, validate, minify and sort JSON online, with the exact parser error when it is invalid. Free, and your JSON never leaves your browser.Regex TesterTest JavaScript regular expressions with flags, see every match and capture group, and preview replacements. Free, and your text stays in your browser.Base64 EncoderEncode text to Base64 or decode it back, with UTF-8 support and ready-to-paste data URIs for CSS and HTML. Free, and nothing leaves your browser.Number ConverterConvert numbers between binary, octal, decimal and hexadecimal, with 8- to 64-bit word sizes and two's complement. Free and works in your browser.API Response & XML FormatterFormat or minify XML and JSON API responses, and check validity, top-level keys, nesting depth and size. Free, and responses stay in your browser.JWT DecoderDecode a JWT's header and payload, read its claims, and flag expiry, issuer and audience problems. Free, and the token is never sent to a server.JSON to TOON ConverterConvert JSON to TOON, a compact notation for LLM prompts, convert TOON back to JSON, and estimate the token savings. Free and runs in your browser.Editorial Clarity CheckerCheck writing for repeated words, uniform sentence lengths and stock phrases, with practical edits. Runs in your browser; it is not an AI detector.JSON Form BuilderDefine form fields in simple lines, preview the form live, and export the HTML with a matching JSON Schema for validation. Free and made in your browser.Developer Tools WorkspaceDraft an API request with headers, params and a JSON body, get curl and fetch snippets, and test assertions on a sample response. Runs in your browser.