XmlValidator Portable is a handy and reliable utility designed to validate XML documents against XSD schemas. In the left pane you can type, paste or load an XML from an existing file. Without an existing schema just the format can be checked, after you press the "Validate" button in the bottom pane will appear "XML is well formed" or the error message.
If you check "Discover schema from XML" the referenced schema will be used if any. In the right pane you can put the schema definition (XSD) and the validation will give you "XML is valid" or a list of errors.
Requirements:
· .Net framework 4.0