IconVault's XML Formatter takes messy or minified XML and pretty-prints it with clean indentation, or minifies it down for transport. It also validates your document and reports parse errors with line and column numbers, so you can fix malformed feeds, configs and API payloads fast. A built-in XPath query box powered by document.evaluate lets you extract exactly the nodes you need.

Parsing and formatting happen fully in your browser using the native DOMParser, so your data is never uploaded to a server. It is free with no signup and no limits. Honest note: it validates well-formedness, not schema conformance, so it will not check your document against an XSD or DTD.