XML Validator

XML Validator - Validate XML Syntax Online

Our free XML validator allows you to validate XML syntax and check for errors instantly. Perfect for developers, data analysts, and anyone working with XML documents. Get detailed error messages, line numbers, and XML analysis to quickly identify and fix syntax issues.

What is XML Validation?

XML validation is the process of checking XML documents for syntax errors, structural issues, and well-formedness. A validator analyzes your XML to ensure it follows XML syntax rules, has properly nested tags, closed elements, and can be parsed correctly by XML parsers.

How Our XML Validator Works

Our validator:

1. Parses XML syntax using the browser's built-in DOMParser
2. Validates XML structure, syntax, and well-formedness
3. Provides detailed error messages with line and column numbers
4. Detects common XML issues and warnings
5. Provides XML statistics and analysis

Key Features

• Real-time Validation: Validate XML as you type with automatic error checking
• Detailed Error Messages: Get specific error descriptions with line and column numbers
• XML Analysis: View statistics about your XML including element count, attributes, comments, and more
• Warning Detection: Identify common XML issues like missing XML declaration, unclosed tags, and duplicate attributes
• File Upload: Validate XML files directly from your computer
• Sample Code: Load sample XML code to see the validator in action
• Privacy-focused: All validation happens in your browser - your XML never leaves your device

Common Use Cases

• XML Development: Validate XML documents during development
• Data Integration: Check XML data before importing or processing
• API Testing: Validate XML responses from APIs
• Configuration Files: Validate XML configuration files
• Learning: Validate XML code while learning the language
• Debugging: Identify syntax errors that prevent XML from being parsed
• Pre-deployment: Validate XML before deploying to production
• Education: Help students understand XML syntax errors

Understanding Validation Results

Valid XML

When your XML is valid, you'll see:

• A green checkmark indicating valid, well-formed XML
• XML statistics (lines, characters, elements, attributes, etc.)
• Any warnings about XML quality issues (if present)
• Validation summary with detailed information

Invalid XML

When errors are detected, you'll see:

• A red error indicator
• Detailed error message explaining the issue
• Line and column numbers where the error occurs (when available)

Warnings

The validator also detects common XML quality issues:

• Missing XML Declaration: XML should start with <?xml version="1.0"?>
• Missing Encoding: Encoding declaration is recommended in XML declaration
Unclosed Tags: All opening tags must have corresponding closing tags
• Duplicate Attributes: Elements should not have duplicate attribute names

XML Well-Formedness Rules

For XML to be valid, it must follow these rules:

1. Single Root Element: XML must have exactly one root element
2. Proper Nesting: Elements must be properly nested (no overlapping tags)
3. Closed Tags: All elements must have closing tags or be self-closing
4. Attribute Quotes: All attribute values must be quoted (single or double quotes)
5. Case Sensitivity: Opening and closing tags must match exactly (case-sensitive)
6. Special Characters: Special characters like <, >, & must be properly escaped

Example: Valid XML

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
    <book id="1">
        <title>The Great Gatsby</title>
        <author>F. Scott Fitzgerald</author>
        <year>1925</year>
    </book>
</bookstore>

Example: Invalid XML

<?xml version="1.0"?>
<bookstore>
    <book id="1">
        <title>The Great Gatsby</title>
        <author>F. Scott Fitzgerald</author>
        <year>1925</year>
    <!-- Missing closing </book> tag -->
</bookstore>

Tips for Using the XML Validator

• Start with XML Declaration: Always include <?xml version="1.0" encoding="UTF-8"?> at the start
• Check Tag Matching: Ensure all opening tags have corresponding closing tags
• Verify Attributes: Make sure all attributes are properly quoted
• Review Error Messages: Pay attention to line and column numbers for quick error location
• Use File Upload: For large XML files, use the file upload feature
• Check Warnings: Review warnings even if XML is valid - they may indicate best practice violations