What is XML Validator?
XML Validator is a free online tool that validates, formats, and beautifies XML documents. Whether you're working with RSS feeds, web services, configuration files, or any XML-based data, this tool helps ensure your XML is syntactically correct and properly formatted.
Our validator uses a real XML parser to check your code against the official XML specification, providing detailed error messages with line numbers when issues are found.
Why Use XML Validator?
- Instant Validation — Check XML syntax in real-time as you type
- Beautiful Formatting — Automatically indent and beautify your XML
- Detailed Errors — Get specific error messages with line numbers
- Statistics — View line count, element count, and file size
- Multiple Formats — Beautify, compact, or minify your XML
- Free & Secure — All processing happens in your browser
XML Syntax Rules
Valid XML must follow these rules:
- Root Element — Every XML document must have exactly one root element
- Proper Nesting — Tags must be properly nested (no overlapping)
- Closing Tags — All tags must be closed, including self-closing tags
- Quoted Attributes — All attribute values must be in quotes
- Case Sensitivity — XML is case-sensitive (
<Title>is different from<title>) - Single Root — Cannot have multiple root-level elements
How to Use
- Paste XML — Copy and paste your XML code into the input area
- Choose Options — Select formatting preferences (beautify, compact, etc.)
- Click Validate — The tool validates your XML and shows results
- View Errors — If invalid, see detailed error messages below
- Copy Output — Use the copy button to get formatted XML
XML Formatting Options
Beautify (Format)
Adds proper indentation and line breaks to make your XML readable:
<root>
<item>
<name>Value</name>
</item>
</root>Compact (Minify)
Removes all unnecessary whitespace for smaller file size:
<root><item><name>Value</name></item></root>Common XML Errors
| Error | Description |
|---|---|
| Unclosed Tags | Missing closing tag or self-closing syntax |
| Improper Nesting | Overlapping tags like <a><b></a></b> |
| Missing Root | Document has multiple root elements |
| Unquoted Attributes | Attribute values without quotes |
| Special Characters | Unescaped <, >, or & |
| Invalid Characters | Characters not allowed in XML names |
Escaping Special Characters
These characters must be escaped in XML:
| Character | Entity |
|---|---|
| < | < |
| > | > |
| & | & |
| " | " |
| ' | ' |
Use Cases
- API Development — Validate XML responses from web services
- RSS/Atom Feeds — Ensure feeds are properly formatted
- Configuration Files — Check XML config files before deployment
- Data Exchange — Validate XML data for EDI or B2B transactions
- Learning XML — Understand proper XML structure
Frequently Asked Questions
Is my XML data sent to a server?
No. All validation and formatting happens entirely in your browser using JavaScript. Your XML data never leaves your device, ensuring complete privacy.
What's the difference between well-formed and valid XML?
Well-formed XML follows XML syntax rules (proper tags, nesting, etc.). Valid XML additionally conforms to a specific schema (DTD or XSD) that defines allowed elements and structure.
Can I validate XML against a schema?
This tool validates XML for well-formedness. For schema validation, you would need additional tools like XMLSpy or oXygen XML Editor.
Why should I format my XML?
Formatted XML is easier to read, debug, and maintain. Compact XML is useful for API responses where bandwidth matters.