XML well-formedness checker and validator

Use this form to check an XML document for well-formedness and (optionally) DTD-validity. External entity references are included, even when not validating. If the document is well-formed, the parser outputs the corresponding canonical XML.

This service is provided for occasional checking of XML documents. Any other use is prohibited. Note that we keep detailed log files and report all suspected abuses to the relevant authorities.

The checker uses the RXP parser, written by Richard Tobin. RXP is part of the LT-XML 2 system, which is available from the Language Technology Group at the University of Edinburgh.

If you find yourself using this service frequently, I suggest you download RXP or LT-XML 2 and use it locally.


do namespace processing?

XML namespaces don't mesh well with DTD-based validity, so you quite likely won't want to select both validation and namespace processing.

Only HTTP URLs are allowed. They are fetched through a proxy, which might conceivably cache old versions, though as far as I know it doesn't.

Thanks to Glenn 'devalias' Grant for pointing out a problem with this checker (now fixed).