XML Formatter & Validator
Format, validate and pretty-print XML documents.
Paste your XML payload to instantly reformat it with consistent indentation or validate it strictly against the W3C XML specification. If the document is invalid, you get the exact line and column number of the parsing failure so you can fix it quickly without staring at a wall of text.
Formatting runs entirely in memory on our secure server, and the parsed result is returned within the exact same HTTP request. Absolutely nothing is stored: your highly sensitive XML is never written to disk, never logged to a database, and never shared with any third-party analytics services.
How it works
The tool attempts to parse your raw input utilizing PHP's native libxml extension configured in strict validation mode. Valid documents are loaded into an abstract DOM tree and then carefully re-serialized with consistent indentation, proper escaping, and clean line breaks. This makes incredibly dense, machine-generated XML payloads instantly readable by human engineers.
If the XML is malformed, the underlying C parser halts execution and returns the precise line and column of the fatal failure, along with the specific error message generated by the XML engine. Common causes of invalid XML include unclosed tags, mismatched casing in tag names (XML is strictly case-sensitive), missing root wrapper elements, or unescaped HTML characters like & and < hiding inside text nodes.
Frequently asked questions
Is my XML payload uploaded or stored anywhere?
No. Your input is processed in volatile memory during the brief lifecycle of the request and discarded immediately after the response is sent back. It is never written to a persistent disk or sent to any third-party APIs.
What is the absolute maximum size I can format?
Two megabytes per request. For gigabyte-sized XML database dumps, you should use a streaming command-line tool like xmllint instead of a web browser, which would simply freeze trying to render that much text.
Why does it say "Extra content at the end of the document"?
A strictly valid XML document must possess exactly one root element that completely encloses everything else. If you mistakenly paste two separate XML blocks or multiple sibling root tags, the strict parser will outright reject it.
Does this check XML against an XSD schema or DTD?
No, this specific tool performs syntax validation (checking if the document is strictly "well-formed" XML syntax) but does not fetch or validate against external DTDs or XSD schema definitions.
Why are my empty tags automatically collapsed?
When the DOM tree is re-serialized, tags that contain absolutely no text or child nodes (like <code><item></item></code>) are automatically collapsed into standard self-closing tags (<code><item/></code>). This is standard XML behavior and is semantically identical.
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