XML Editor is a user-friendly, straightforward, and powerful graphical XML editing and validation tool. It supports Unicode, allowing users to work with XML in any language. XML Editor provides full DTD validation, but it is also possible to do well-formedness validation without a DTD. It provides meaningful messages that point out conflicts with the XML file and the DTD, and explains why the XML file conflicted the DTD. It can also detect other types of errors in XML. It has two viewing modes, "Tree" and "Source", which allow for text editing of XML.
Blinged JSON Validator is a free app to validate JSON files with syntax highlighting, whitespace indentation, error messaging, and hotkeys.
