Format, encode, convert and debug — faster.
A complete toolkit for engineers: JSON formatters, encoders, hash generators, JWT decoders and more. Everything runs locally in your browser, so your data never leaves your device.
Popular Developer tools
JSON Formatter & Validator
Beautify, minify and validate JSON with clear error reporting.
Base64 Encode / Decode
Convert text and files to and from Base64 in one click.
URL Encode / Decode
Percent-encode and decode URLs and query parameters.
UUID Generator
Generate cryptographically random UUID v4 identifiers.
Regex Tester
Test regular expressions live with match highlighting and capture groups.
Unix Timestamp Converter
Convert Unix timestamps to human dates and back, in local and UTC time.
Hash Generator
Compute SHA-1, SHA-256, SHA-384 and SHA-512 hashes.
JSON to CSV Converter
Convert between JSON arrays and CSV with proper quoting and parsing.
JWT Decoder
Decode and inspect JSON Web Token headers and payloads.
HTML Entity Encode/Decode
Encode and decode HTML entities, including numeric and named references.
Color Contrast Checker
Check WCAG color contrast ratios with AA and AAA pass/fail results.
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal.
Newest
HTML Entity Encode/Decode
Encode and decode HTML entities, including numeric and named references.
Unix Timestamp Converter
Convert Unix timestamps to human dates and back, in local and UTC time.
Number Base Converter
Convert numbers between binary, octal, decimal and hexadecimal.
Regex Tester
Test regular expressions live with match highlighting and capture groups.
Learn about Developer
Understanding JSON: A Practical Guide for Developers
What JSON is, how it is structured, and the common mistakes that break parsers — with examples you can fix in seconds.
Base64 Encode and Decode: A Practical Developer Guide
Learn how Base64 encoding works, when to use it, and how to safely encode text, files, and data URLs right in your browser.
URL Encode and Decode: Percent-Encoding Done Right
Understand percent-encoding, the difference between encoding a component and a full URL, and how to avoid broken query parameters.
UUID Generator: Random v4 IDs You Can Trust
Learn what UUID v4 identifiers are, why they are practically unique, and how to generate cryptographically random IDs in bulk.
Hash Generator: SHA-256 and Friends in Your Browser
Compute SHA-1, SHA-256, SHA-384, and SHA-512 hashes locally and learn when each algorithm is the right choice.
JWT Decoder: Read and Debug JSON Web Tokens
Decode a JWT header and payload, inspect claims like exp and iss, and understand why decoding is not the same as verifying.
HTML Entity Encode and Decode: Escape Safely
Learn how HTML entities work, why escaping prevents XSS and layout breaks, and how to convert named, decimal, and hex entities.
Unix Timestamp Converter: Epoch to Human Time
Convert Unix timestamps to human-readable dates and back, handle seconds vs milliseconds, and work confidently across time zones.
Number Base Converter: Binary, Hex, Octal, Decimal
Convert numbers between binary, octal, decimal, and hexadecimal with BigInt-safe precision for very large values.
Regex Tester: Build and Debug JavaScript Patterns
Test JavaScript regular expressions with live highlighting, inspect capture groups, and learn the flags that change everything.
JSON to CSV Converter: Clean, Quoted, Two-Way
Convert JSON arrays to CSV and CSV back to JSON with correct quoting, escaping, and header handling for spreadsheets.
Color Contrast Checker: Pass WCAG AA and AAA
Check text and background contrast ratios against WCAG AA and AAA thresholds to build accessible, readable interfaces.
Developer FAQ
Yes — every tool is free with no account required.
Most tools run entirely in your browser, so once the page loads they keep working without sending your data anywhere.