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 and minify JSON, with exact error lines and fix hints.
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.
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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