Free online developer tools

Format and validate JSON and XML, encode and decode Base64, URLs and HTML, minify code, and generate UUIDs and slugs — fast, private and in your browser.

JSON Formatter & Validator Format, validate and minify JSON with clear error locations. XML Formatter & Validator Indent, validate and minify XML documents. Base64 Encoder / Decoder Encode text or files to Base64 and decode it back. HTML / CSS / JS Minifier & Beautifier Minify or beautify HTML, CSS and JavaScript code. HTML Escape / Unescape Convert special characters to HTML entities and back. URL Encoder / Decoder Percent-encode or decode URLs and query strings. UUID Generator Generate random version 4 UUIDs in bulk. Slug Generator Turn titles into clean, URL-friendly slugs. Domain Age Checker Look up when a domain was registered and when it expires.

What’s in the toolbox?

Formatting and validation — JSON Formatter and XML Formatter pretty-print, minify and point to the exact line and column of any error.
Encoding — Base64 (text and files, Unicode-safe), URL encoding and HTML escaping.
Front-end code — HTML/CSS/JS Minifier & Beautifier, using Terser for JavaScript.
Generators — UUID Generator (v4 and time-ordered v7) and Slug Generator.
Domains — Domain Age Checker looks up registration dates via the public RDAP system.

Safe for real data

Pasting API responses, tokens or config into an online formatter can leak secrets if the site logs input. These tools run entirely in your browser — nothing you paste is sent to a server. The only exception is the domain checker, which sends just the domain name to an RDAP registry.

Frequently asked questions

Is it safe to paste JSON containing API keys?

The formatter runs locally and doesn’t send your input anywhere. As a general habit, still rotate any key you’ve pasted into a tool you don’t control.

Do the tools work offline?

Once a page has loaded, the formatting and encoding tools keep working without a connection.

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