Format, minify, and validate XML with syntax highlighting. All processing runs in your browser without any server uploads.
Key Features of XML Formatter
- Pretty-Print & Minify Switch between formatted (indented) and minified (compact) XML output with a single dropdown. Useful for both readability and reducing payload size.
- Live Syntax Validation The tool validates your XML on every keystroke using the browser's native DOMParser. Malformed tags, unclosed elements, and encoding errors are flagged immediately.
- Monaco Editor with XML Highlighting Both the input and output panels use the same Monaco editor that powers VS Code, with full XML syntax highlighting for tags, attributes, values, and comments.
- File Upload Support Upload an .xml file directly into the input panel without copy-pasting. Useful for large or complex XML documents.
- One-Click Copy & Privacy Copy the formatted output to your clipboard with one click. All processing runs in your browser — no data is ever sent to a server.
XML Formatter Examples
Pretty-Printing a Minified XML Response
Take a compact XML API response and expand it into a human-readable, indented format.
Input
<catalog><book id="1"><title>Clean Code</title><author>Robert C. Martin</author></book></catalog>
Output
<catalog>
<book id="1">
<title>Clean Code</title>
<author>Robert C. Martin</author>
</book>
</catalog>
Catching a Malformed Tag
Paste XML with an unclosed tag to see the live validation error highlight the problem immediately.
Input
<root><item>value</root>Output
Validation error: element item was opened but not closed.How to Use XML Formatter
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1. Paste XML into Input
Type or paste raw or minified XML into the input panel.
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2. Automatic Format & Validate
The formatter automatically validates your XML structure and pretty-prints it with proper indentation.
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3. Copy or Download
Copy the formatted XML to your clipboard or download it as a .xml file.
Common Use Cases for XML Formatter
- Debugging API Responses Many SOAP services, RSS feeds, and legacy REST APIs return minified or poorly indented XML. Paste the response into the formatter to instantly make it readable.
- Editing Configuration Files XML config files (Maven pom.xml, Spring application context, Android manifests) can become dense. Use the formatter to pretty-print and spot structural issues before committing.
- Validating XML Before Integration Catch malformed XML early. The live validator highlights errors before you send data to a downstream service or import it into a database.
- Minifying for Production Remove all unnecessary whitespace from XML payloads to reduce file size and transmission time when calling XML-based APIs.
The Technical Details
Validation uses the browser’s built-in DOMParser with MIME type application/xml. If the parsed document contains a <parsererror> element, the XML is invalid and the error message is extracted and displayed.
Pretty-printing works by first minifying the raw XML (collapsing all whitespace between tags), then splitting on tag boundaries. Each node is classified as an opening, closing, or self-closing tag to determine whether indentation depth should increase, decrease, or stay the same. Two spaces are prepended per depth level.
Minification reverses this: a single regex replaces all whitespace sequences between > and < with nothing, producing a compact single-line string.
Frequently Asked Questions
What is the difference between XML and HTML?
XML is a strict, self-describing data format where you define your own tags. HTML is a fixed-tag language for web content. XML requires all tags to be properly closed and nested.
Can I adjust the indentation?
Yes. The tool supports 2-space, 4-space, and tab indentation options.
Is any data sent to a server?
No. All formatting and validation runs in your browser. Nothing is ever sent to a server.
Can it handle large XML files?
The tool processes XML in-memory in your browser. While large files are handled locally, processing very large datasets may take a few seconds.