Developer calculators and tools
JSON, text, CSV, hashes, URLs, JWTs, regex and more — all local. 31 tools.
JSON
JSON FormatterPretty-print JSON with 2 or 4 spaces or tabs and optional key sorting — numbers are never altered.JSON ValidatorCheck whether JSON is valid, with the exact line and column of any error and structure statistics.JSON MinifierRemove all unnecessary whitespace from JSON and see how many bytes you saved.
Encoding, hashing and tokens
Base64 Encode and DecodeEncode text to Base64 or decode Base64 to text, with URL-safe output and full Unicode support.URL Encode and DecodePercent-encode or decode URLs and query values — as a component, a full URL or form data.HTML Entity Encoder and DecoderEscape text for HTML or decode entities like & and © back to characters.Hash GeneratorGenerate SHA-256, SHA-384, SHA-512 and SHA-1 hashes of any text, in your browser.JWT DecoderRead a JWT's header and payload locally. The signature is not verified.UUID GeneratorGenerate random UUID v4 or time-ordered UUID v7 values in bulk, in your browser.Unix Timestamp ConverterConvert Unix timestamps (seconds or milliseconds) to dates and dates to timestamps, in UTC or local time.
Code and text
Regex TesterTest a regular expression against text with highlighted matches, capture groups and a replace preview.Text Diff CheckerCompare two texts line by line and see exactly what was added and removed.Markdown PreviewerPreview Markdown as you type and copy the HTML it produces, safely, in your browser.HTML FormatterIndent and tidy HTML without changing its tags, attributes or text.CSS FormatterFormat CSS with consistent indentation, or minify it, with errors that give the line number.Slug GeneratorTurn a title into a clean URL slug: lowercase, accents removed, words joined with hyphens.
Text cleanup and lists
Count, clean, sort, deduplicate and replace text.
Word CounterCount words, characters, sentences and paragraphs, with reading time and the most-used words.Case ConverterConvert text to UPPER, lower, Title, Sentence, camel, Pascal, snake, kebab and CONSTANT case.Remove Duplicate LinesNewDelete repeated lines from a list and keep one copy of each, in your browser.Sort Lines AlphabeticallyNewSort a list of lines A to Z, Z to A, by number or length, or shuffle them.Find and Replace TextNewFind words or patterns in your text and replace them, with case and regex options.Remove Extra SpacesNewClean pasted text: collapse repeated spaces, trim lines, drop blank lines or join lines.
Data conversion and generators
CSV to JSON ConverterConvert CSV or spreadsheet data to JSON, with delimiter detection and type conversion.JSON to CSV ConverterConvert a JSON array of objects to CSV for Excel or Google Sheets, with nested fields flattened.Password GeneratorGenerate strong random passwords with your browser's secure random generator, never sent anywhere.Lorem Ipsum GeneratorGenerate lorem ipsum placeholder text by paragraphs, sentences or words, instantly.
Web, colour and scheduling
URL ParserSplit a URL into scheme, host, port, path, query parameters and fragment.Color ConverterConvert colours between HEX, RGB, HSL and HSV, with WCAG contrast ratios against white and black.Contrast CheckerCheck the contrast ratio of text and background colours against WCAG AA and AAA.Cron Expression ExplainerTranslate a 5-field cron expression into plain English and list its next run times.QR Code GeneratorMake a QR code for a link, text, contact, email, phone or SMS, as PNG or SVG.
About these developer tools
Everything on these pages runs in your browser. The JSON, tokens, text and code you paste are processed on your device and are never uploaded, stored or sent to analytics, so it is safe to paste real payloads while debugging. Share links are switched off for these tools for the same reason.
Where behaviour differs between environments the page says so — the JSON tools follow the JSON specification strictly, the regex tester uses JavaScript's engine, and the JWT decoder only decodes: it never claims a token is valid.