Developer tools
Formatters, converters, encoders and generators for daily development work. Input stays in your browser: there is no "save" link and no server copy, so tokens, configs and logs cannot leak from here.
JSON Formatter & Validator
Format, validate, minify and explore JSON: tree view, search, exact error lines.
CSV to JSON Converter
Convert CSV or TSV into a JSON array, with types and headers detected.
JSON to CSV Converter
Turn a JSON array into CSV for Excel or Sheets, flattening nested fields.
YAML ⇄ JSON Converter
Convert YAML to JSON and JSON to YAML, with clear error positions.
Base64 Encode & Decode
Encode text to Base64 or decode Base64 back to text or a file, UTF-8 safe.
URL Encoder & Decoder
Percent-encode or decode URLs and query strings, and inspect parameters.
JWT Decoder
Decode a JSON Web Token locally and verify its signature with your key.
UUID Generator
Generate random v4 or time-ordered v7 UUIDs in bulk, and inspect any UUID.
Hash Generator
MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or files, plus HMAC.
Regex Tester
Test JavaScript regular expressions with live highlighting, groups and replace.
Unix Timestamp Converter
Convert epoch seconds or milliseconds to dates, and dates to timestamps.
SQL Formatter
Beautify SQL queries for PostgreSQL, MySQL, SQL Server, SQLite and more.
Markdown to HTML
Convert Markdown to clean HTML with a live, safe preview.
Number Base Converter
Convert between binary, octal, decimal, hex and any base from 2 to 36.
Image to Base64
Turn an image into a Base64 data URL, CSS background or HTML img tag.
CSV to Excel Converter
Turn CSV files into real .xlsx workbooks without mangling codes, IDs or leading zeros.
Excel to CSV Converter
Export every sheet of an .xlsx workbook to clean, standard CSV.
Excel to JSON Converter
Turn spreadsheet rows into JSON objects, keeping numbers, booleans and dates.
JSON to Excel Converter
Turn a JSON array into an .xlsx sheet; nested fields become columns.
Split CSV
Cut a large CSV into smaller files, with the header in each.
Create ZIP File
Bundle files into one ZIP on your device. Nothing is uploaded.
Unzip Files
Open a ZIP in your browser, see what is inside and save the files you need.
XML Formatter & Validator
Pretty-print or minify XML and get the exact line of any error.
JSON to XML Converter
Convert JSON to well-formed XML, with attributes and arrays handled.
XML to JSON Converter
Convert XML to JSON with attributes, repeated elements and text handled predictably.
HTML Formatter
Beautify messy or minified HTML, including the CSS and JavaScript inside it.
CSS Formatter & Minifier
Beautify CSS, SCSS or Less, or minify CSS and see the bytes saved.
JavaScript Formatter & Minifier
Beautify JavaScript and TypeScript, or minify JavaScript with Terser.
HTML Entity Encoder & Decoder
Escape text for HTML, or turn &-style entities back into characters.
Cron Expression Explainer
See what a cron schedule means in plain English and when it runs next.
No developer tool matches that word.
Developer tools: common questions
Do the developer tools send my data to a server?
No. Tokens, JSON, SQL and hashes are processed in your browser. That makes the JWT decoder and hash generator safe for real tokens and files, but never paste secrets into a page you do not trust.
Do the tools validate as well as convert?
Yes. JSON, YAML and CSV input is parsed strictly; errors name the line and column where possible, and invalid input never produces a silent result.
Can I convert many values at once?
Yes. Base64, URL encoding, hashes, timestamps and number bases have a bulk mode that converts one value per line and exports the results as CSV.
Related guides
Base64 and Data URLs: When to Inline Images (and When Not)
What Base64 is, why it makes data about 33% bigger, how data URLs work in HTML and CSS, and when inlining an image speeds a page up or slows it down.
Read the guideHow to Check if an Online Tool Uploads Your Files
A 2-minute test with your browser’s developer tools shows whether a PDF or image tool sends your file to a server. Step by step, for Chrome, Edge, Firefox and Safari.
Read the guideCommon JSON Errors and How to Fix Them
Trailing commas, single quotes, comments, NaN and unescaped line breaks: the JSON mistakes that break parsers, why they are invalid, and how to fix each one.
Read the guide