XML Validator
Check if your XML is well-formed. Get instant error messages with exact locations.
XML Validator Features
Instant, private XML validation in your browser.
Validates all XML syntax rules including tag nesting, attribute quoting, and single root element.
When XML is invalid, shows the precise error message from the browser's XML parser.
Your XML stays on your device. Privacy-aware, no sign-up needed.
Key Takeaways
- Validation runs entirely in your browser using the built-in DOMParser, so your XML stays on your device, making it safe for sensitive config files.
- It checks well-formedness only - closed and correctly nested tags, a single root element, quoted attributes, proper escaping of special characters, and declared namespace prefixes.
- It does not perform schema validation against a DTD or XSD, so a passing result confirms valid syntax but not conformance to a defined structure; use a server-side schema validator for that.
- When XML fails, it reports the first parser error message along with the root element name and total element count, helping you pinpoint unclosed tags, stray characters, or bad nesting.
How to Validate XML in Your Browser
Paste Your XML
Copy your XML document or fragment into the input area. The validator reads the whole text you paste, so include the XML declaration and the single root element if you have them. Everything stays on your device.
Click Validate XML
Press the Validate XML button. The tool parses your text with the browser's built-in DOMParser and checks for well-formedness: closed tags, correct nesting, quoted attributes, and one root element.
Read the Result
A green banner confirms valid XML and reports the root element name plus the total element count. A red banner shows the first parser error message so you can jump straight to the problem. Use Clear to reset and check another document.
What This Validator Checks and What It Does Not
This tool verifies well-formedness using the same XML parser your browser ships with. It does not perform schema validation against a DTD or XSD. The table below shows where each rule falls so you know what a passing result actually guarantees.
| Rule or Feature | Checked Here | Notes |
|---|---|---|
| Tags closed and correctly nested | Yes | Mismatched or unclosed tags are reported as errors. |
| Single root element | Yes | Multiple top-level elements fail well-formedness. |
| Attribute values quoted | Yes | Unquoted attribute values trigger a parser error. |
| Escaping of and , and special characters | Yes | Raw and or unescaped less-than signs are flagged. |
| Namespace prefixes declared | Yes | Undeclared xmlns prefixes cause an error. |
| Conformance to a DTD or XSD schema | No | Schema validation needs a separate server-side tool. |
Is This the Right Tool for Your Task
Quick Syntax Check
If you just need to confirm an XML file parses cleanly before using it, this is ideal. You get the root name and element count the moment it is well-formed.
Debugging a Parse Error
When another program rejects your XML, paste it here. The first parser error message points you to the unclosed tag, stray character, or bad nesting causing the failure.
Sensitive Config Files
Because validation runs entirely in your browser with DOMParser, the content stays on your device. That makes it suitable for checking config files without uploading them.
Schema or DTD Validation
If you must confirm the document matches a defined XSD or DTD structure, this tool is not enough. Use a dedicated schema validator that supports those grammars.
Common Problems and Fixes
Error mentions an extra content at the end of the document
This usually means you have more than one root element. Wrap all top-level elements in a single container element so the document has exactly one root.
Error about an unexpected character or entity
A raw and, less-than, or greater-than sign in your text breaks parsing. Replace them with &, <, and >, or place the content inside a CDATA section.
Result says a tag was not closed
Check that every opening tag has a matching closing tag and that nesting is correct. Self-closing elements must end with a slash, such as a br element written as a slash before the closing bracket.
Namespace prefix error appears
Every prefix used on an element or attribute must be declared with a matching xmlns attribute in scope. Add the missing xmlns declaration on the element or an ancestor.
What Makes XML Well-Formed?
Well-formed XML must follow strict syntax rules: every tag must be closed, tags must be properly nested, attribute values must be quoted, and the document must have exactly one root element. Our free XML validator instantly checks all these rules and reports any errors.
Frequently Asked Questions
What is XML validation?
XML validation checks whether an XML document follows the rules of the XML specification.
The minimum requirement is that XML must be well-formed - correct syntax, closed tags, and a single root element.
Additional validation against a schema (DTD or XSD) checks that element names and structure match a defined format.
What are common XML errors?
The most common errors are unclosed tags (forgot ), mismatched tags, and special characters like & and < that must be written as & and <.
Other common issues include attributes without quotes and multiple root elements.
Our validator gives the exact error message from the XML parser so you can quickly find and fix the issue.
What is the difference between well-formed and valid XML?
Well-formed XML follows the basic XML syntax rules. Any XML parser can read it.
Valid XML additionally conforms to a DTD or XML Schema (XSD), which defines what elements and attributes are allowed.
This tool checks well-formedness. For schema validation you need a server-side tool.
Why does my XML need a root element?
XML documents must have exactly one root element that contains all other elements.
If you have multiple top-level elements, wrap them in a single container element.
For example, wrap multiple
How do I escape special characters in XML?
Five characters must be escaped in XML: & → &, < → <, > → >, “ → ", ' → '.
Failing to escape these characters is the most common cause of XML parsing errors.
Alternatively use CDATA sections: to include unescaped text.
Is my data private?
Yes. All XML validation happens in your browser using the built-in DOMParser API.
No data is sent to any server. This makes the tool safe for sensitive configuration files.
We do not log, store, or transmit any content you paste into the tool.
Can I validate XML with namespaces?
Yes. The browser's XML parser fully supports XML namespaces.
Make sure namespace declarations (xmlns: attributes) are correct and prefixes are properly declared.
Undeclared namespace prefixes will cause a validation error.
What does the green success message show?
When your XML is valid, a green banner shows the root element name and total element count.
This confirms that the document is well-formed and can be parsed by any standard XML parser.
You can then use a formatter or other tool to further process your validated XML.
Sources and References
Format and tool details on this page are based on the official specifications and documentation below.
- Extensible Markup Language (XML) 1.0- W3C
- XML introduction- MDN Web Docs