The XML Validator checks whether your XML document is well-formed — meaning all tags are properly opened and closed, elements are correctly nested, and special characters are properly escaped. Well-formed XML is a prerequisite for parsing by any XML processor, API, or configuration system. This tool uses the browser's built-in DOMParser to analyze your XML and reports any syntax errors with descriptive messages, helping you quickly identify and fix issues. Whether you are preparing configuration files, debugging API responses, or validating data feeds, this tool provides instant feedback. All validation runs entirely in your browser — your XML is never sent to a server.
About XML Validator
XML (eXtensible Markup Language) requires strict syntax rules to be considered "well-formed." Every opening tag must have a corresponding closing tag (or be self-closing), elements must be properly nested (you cannot close a parent element before its children), and special characters like < and & in text content must be escaped as entities. A well-formed XML document can be successfully parsed by any XML processor.
This validator checks your XML against these fundamental rules using the browser's native DOMParser. If the XML is valid, you get a confirmation. If there are errors, you get a descriptive message indicating the type and location of the problem. Note that this tool checks for well-formedness only — it does not validate against a DTD (Document Type Definition) or XSD (XML Schema Definition). All processing runs in JavaScript within your browser.
How to Use XML Validator
- Paste or type your XML into the input area.
- Click Validate XML to check the syntax.
- If the XML is well-formed, you will see "Valid XML." If there are errors, a descriptive message indicates the problem.
- Fix any reported issues and validate again until the XML passes.
Key Features
- Well-formedness check — Verifies tags, nesting, and character escaping
- Descriptive error messages — Helps you locate and understand syntax issues
- Instant validation — Results appear immediately after clicking Validate
- Browser-native parsing — Uses the DOMParser for reliable, standards-compliant checking
- Client-side privacy — No data leaves your browser; safe for sensitive XML
When to Use This Tool
- Validating configuration files (web.xml, pom.xml, .csproj) before deployment
- Checking API request or response XML for syntax errors during development
- Verifying XML data feeds, RSS feeds, or sitemap files
- Quick syntax check before importing XML into databases or processing pipelines
- Learning XML by experimenting with document structure and seeing error feedback
Technical Details
The validator uses the browser's DOMParser with the application/xml content type. When parsing fails, the DOMParser produces a document containing a <parsererror> element with a description of the error. The tool extracts this message and displays it to you. Common errors include: unclosed tags, mismatched opening and closing tag names, unescaped < or & in text content, and invalid characters. This is a well-formedness check only — it does not validate against DTD or XSD schemas. All processing runs in JavaScript within your browser.
Conclusion
XML Validator is a quick, reliable tool for checking whether your XML is well-formed before using it in production systems. With descriptive error messages, standards-compliant parsing, and complete browser-side privacy, it helps you catch and fix XML syntax issues instantly. For formatting your XML, use the XML Formatter.