How to Validate XML
XML Validation
When to Validate XML
Validate XML before deploying configs, parsing API responses, or importing legacy data. Catch unclosed tags, invalid characters, and malformed declarations early instead of at runtime when strict parsers reject the document.
Common XML Errors
- Unclosed or mismatched start/end tags
- Invalid characters in element text or attribute values
- Malformed XML declarations or namespace prefixes
- Duplicate attributes on a single element
Developer Tips
- Validate in CI before deploying XML-based configs or SOAP integrations
- Format after fixing errors for readable error context around the failure
- Schema validation (XSD) requires a separate tool — this checks syntax only
Frequently asked questions
What errors are detected?
Unclosed tags, invalid characters, malformed declarations, and other well-formedness issues are reported with parser messages.
Is external entity expansion performed?
No. Parsing is limited to pasted text for safety — external entities are not fetched.