XML validation is the process of checking a document written in XML (eXtensible Markup Language) to confirm that it is both well-formed and also "valid" in that it follows a defined structure. A well-formed document follows the basic syntactic rules of XML, which are the same for all XML documents.^[1] A valid document also respects the rules dictated by a particular DTD or XML schema.^[2] Automated tools – validators – can perform well-formedness tests and many other validation tests, but not those that require human judgement, such as correct application of a schema to a data set.

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• OASIS CAM is a standard specification that provides contextual validation of content and structure that is more flexible than basic schema validations.
• Schematron, a method for advanced XML validation.

• xmllint is a command line XML tool that can perform XML validation. It can be found in UNIX / Linux environments.
• XML toolkit. The XML C parser and toolkit of Gnome – libxml includes xmllint
• XML Validator Online Validate your XML data.
• XML Schema Validator Validate XML files against an XML Schema.