XSD Validator: Validate XML Against a Schema Online
An XSD validator checks an XML document against an XML Schema Definition: element structure, order, data types, required attributes, and enumerations. Paste your XML and XSD side by side and validate; every violation is reported with its line number and the exact schema rule it breaks. Validation runs on a full W3C-compliant schema processor (lxml), not a regex approximation.
How it works
- 1
Paste (or upload) the XML document on the left and the XSD schema on the right.
- 2
Click Validate Against Schema.
- 3
Read the verdict: valid, or a line-numbered list of every schema violation.
Frequently asked questions
How do I validate XML against an XSD online?
Paste both documents above and click Validate. The tool first checks that both are well-formed XML, then compiles the XSD into a schema, then validates the document against it, reporting errors from whichever stage fails, with line numbers.
What does an XSD actually check?
Structure (which elements may appear where, in what order, how many times), data types (xs:int, xs:date, xs:decimal and 40+ others), required vs optional elements and attributes, enumerated value lists, and pattern restrictions. A well-formed document can still be invalid against its schema.
Why does my valid-looking XML fail validation?
The most common causes: elements in the wrong order (xs:sequence is order-sensitive), a missing namespace declaration so elements don't match the schema's targetNamespace, values that violate the declared type (letters in an xs:int), and missing required attributes.
Does the validator support XSD 1.1?
Validation is XSD 1.0, which covers the vast majority of real-world schemas including all WSDL type sections. XSD 1.1 features (assertions, conditional type assignment) are not evaluated.
Are my XML and XSD stored anywhere?
No. Both documents are validated in memory and discarded. Nothing is logged or persisted.
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