Developer Tools
20 tools
Formatters, validators, encoders, hashes, and converters for everyday dev work.
JSON Formatter Online
Free online JSON formatter — beautify, minify, and explore JSON in a live tree view. 100% browser-based, no upload, no signup, no data leaves your device.
JSON Validator Online
Free online JSON validator — instant pass/fail verdict with the exact line and column of any syntax error. Browser-based, no upload, no signup, no data sent.
HTML Formatter
Clean and indent messy HTML for better readability.
CSS Formatter
Format and organize CSS automatically with configurable brace and indent styles.
SQL Formatter
Beautify SQL queries with proper indentation across Postgres, MySQL, SQLite, and MSSQL dialects.
XML Formatter
Format XML into a clean, readable structure with attribute control.
JSON to XML Converter
Convert JSON data into well-formed XML quickly.
XML to JSON Converter
Transform XML data into clean JSON with attribute preservation options.
Markdown to HTML Converter
Free online Markdown to HTML Converter with a live preview pane — paste GFM, copy sanitized HTML. 100% browser-based, no upload, no signup, no data sent.
HTML to Markdown Converter
Free online HTML to Markdown Converter — paste rich HTML, get clean GFM Markdown. 100% browser-based, no upload, no signup, no data leaves your device.
Base64 Encoder / Decoder
Encode or decode Base64 strings, with UTF-8 and URL-safe variant support.
JWT Decoder
Decode and inspect JWT header and payload safely in the browser. Signature is not verified.
URL Encoder / Decoder
Encode or decode URLs and URL components for safe transmission.
SHA-256 Generator
Generate SHA-256 hashes from text or files using the Web Crypto API.
MD5 Hash Generator
Create MD5 hashes for text or files. Useful for checksums.
UUID Generator
Generate UUID v4, UUID v7 (time-ordered), and ULID identifiers in bulk with format controls.
Regex Tester
Test regular expressions live with match highlighting, capture groups, replace mode, and a cheatsheet.
YAML Formatter
Format and validate YAML, optionally convert to JSON. Line/column error pointing.
Slug Generator
Convert any title or sentence into a URL-safe slug with diacritic stripping, separator control, and batch mode.
CSV ↔ JSON Converter
Convert between CSV and JSON with proper handling of quoted fields, custom delimiters, and type inference.
About Developer Tools
Developer Tools bundles fifteen utilities that we reach for in everyday engineering work: JSON, HTML, CSS, SQL, and XML formatters; bidirectional converters between JSON and XML; Markdown to HTML and HTML to Markdown; Base64 and URL encoding; JWT inspection; and SHA-256 and MD5 hashing. Each runs locally in your browser using the Web platform and lightweight, audited libraries. Nothing is uploaded — your code, tokens, and payloads stay on your machine.
If you are debugging an API response, sanity-checking a JWT, or pretty-printing a query before pasting it into a ticket, you should find the right tool in two clicks. The formatters use real parsers (not regex) so they preserve semantics, and the syntax-highlighted CodeMirror editor on every formatter page works well with payloads up to several megabytes.
Frequently asked questions
Do these developer tools work on confidential data?+
Yes. Every developer tool runs in your browser using JavaScript — no payload, token, or hash input is transmitted to a server. This is a hard architectural property of the site, not a configuration toggle.
Which SQL dialects does the SQL Formatter support?+
Standard SQL, PostgreSQL, MySQL, SQLite, T-SQL (MSSQL), and BigQuery. Pick a dialect from the dropdown for accurate keyword handling.
Does the JWT Decoder verify the signature?+
No — it only decodes the header and payload so you can inspect claims. Signature verification requires the issuing secret or public key and must be done on the server.
Why use SHA-256 instead of MD5?+
SHA-256 is collision-resistant and is what you want for any security-sensitive use. MD5 is fast and still appropriate for non-security checksums (file integrity within a trusted system).