XML formatting and validity
XML is stricter than HTML: every opening tag must have a corresponding closing tag, attribute values must be quoted, and the document must have exactly one root element. Our formatter parses the XML into a DOM tree and serializes it with configurable indentation (2 or 4 spaces), which also catches structural errors. If the input is malformed, the tool reports the exact line and column of the parsing failure, saving you from hunting through thousands of lines.
Beyond formatting, the tool preserves CDATA sections, processing instructions, and namespace declarations. Namespace prefixes (xmlns) are especially tricky — our formatter maintains the correct namespace context even when elements are deeply nested or when default namespaces change mid-document.
XML vs JSON: when to use each
XML supports attributes, namespaces, schemas (XSD), and mixed content (text + elements in any order), making it more expressive than JSON for complex documents. Use XML when you need document validation, namespaced vocabularies (like SOAP, RSS, or SVG), or when interop with legacy enterprise systems is required. JSON is better for most API payloads because it is lighter and natively parsed by JavaScript.
Our XML formatter helps when you receive minified XML from a legacy API — format it immediately to inspect the structure, then use XPath or XSLT to extract the data you need. The tool also compresses formatted XML back to a compact single line for efficient storage.