About this tool
A malformed XML payload usually fails deep inside a SOAP client or parser with an unhelpful stack trace. This validator parses the document with the browser’s native XML parser and reports the first well-formedness error, with line and column when the browser provides them: unclosed or mismatched tags, an unescaped & or <, duplicate attributes, or more than one root element. When the document is valid it shows the root element and the element count.
How to use it
- Paste the XML, or load the broken sample to see what an error looks like.
- Read the banner: green means well-formed, red gives the parser’s message and location.
- Fix the reported spot (the real mistake is often just before it) and the check re-runs as you type.
XML Validator FAQ
Is this XSD or DTD validation?
No. It checks well-formedness: the syntax rules every XML document must follow. Validating against an XSD (for example a SOAP contract) needs a schema-aware validator in your test framework, such as javax.xml.validation in Java or xmllint with --schema.
Why does the error message differ between browsers?
The check uses the browser’s built-in parser, and Chrome, Firefox and Safari word their errors differently. The location is extracted from whichever format your browser uses; if it does not report one, only the message is shown.
How do I include & or < in text?
Escape them as & and <, or wrap the text in a CDATA section. An unescaped & is the most common cause of “not well-formed” errors in hand-edited test fixtures.