HTML Formatter & Viewer

An HTML formatter is a tool that takes raw, minified, or poorly indented HTML code and restructures it with proper indentation and line breaks. This makes the markup human-readable and easier to debug, edit, and maintain. The formatter parses the DOM tree and outputs each element on its own line with consistent indentation levels.

The HTML viewer renders your HTML code in a sandboxed iframe, showing you exactly how a browser would display the markup. The iframe is isolated with the 'sandbox' attribute, which restricts scripts and external resource loading for security. Toggle the Preview button to switch between the syntax-highlighted code view and the live rendered view.

Yes. After formatting your HTML, click the Preview toggle to see a live rendering of the output in a sandboxed iframe below the output panel. The preview shows the HTML as a browser would render it, including applied CSS styles. Scripts are allowed within the sandbox so you can test interactive elements.

Absolutely. This tool processes everything entirely in your browser using the built-in DOMParser API. No HTML data is ever sent to any server. Your code never leaves your machine, making it safe for proprietary templates, internal tools, and sensitive markup.

Beautify (format) adds proper indentation and line breaks so each HTML element appears on its own line at the correct nesting level. Minify does the opposite: it removes all unnecessary whitespace between tags and collapses text nodes to produce the smallest possible output. Use beautify for development and debugging; use minify for production deployment to reduce file size.

Yes. The formatter includes basic HTML validation that checks for unclosed tags, mismatched opening and closing tags, and unexpected closing tags. It uses a stack-based approach to track tag nesting and reports errors with their positions in the source. Note that this is structural validation, not full W3C specification compliance checking.

Yes. You can choose between three indentation options: 2 spaces, 4 spaces, or tabs. Select your preferred indentation using the buttons in the action bar before clicking Format. The tool will apply your chosen indentation consistently throughout the entire document, including nested elements.

This tool supports full HTML5 documents (with DOCTYPE, html, head, and body tags) as well as HTML fragments (partial markup without the full document structure). It correctly handles void elements (br, hr, img, input, meta, link, etc.), preserves content inside pre, code, script, style, and textarea elements verbatim, and processes HTML comments.