XML Formatter & Validator

The document is read by a parser written on this page that follows the XML 1.0 well-formedness rules: exactly one root element; every start tag closed by a matching end tag in the right order; attribute values quoted and no attribute repeated on an element; "<" and a bare "&" never loose in text or attributes; only the five predefined references (&lt; &gt; &amp; &quot; &apos;) and numeric ones; comments, CDATA sections and processing instructions terminated; the XML declaration first if present. The first violation is reported with its line and column and the offending line, because the point of a validator is to say where.

Formatting rebuilds the tree with the indent you choose: elements that contain only text stay on one line, empty elements are written self-closed, whitespace-only text between elements is dropped and mixed content is trimmed unless you preserve whitespace. Attribute values are re-written in double quotes with any inner quote as &quot;; attributes can be sorted A–Z. Minifying removes the same ignorable whitespace and the line breaks; comments, CDATA and the prolog are kept in both modes. Format → minify → format is stable, which the tests assert.

No validation against a DTD, XML Schema or RELAX NG: a DOCTYPE is carried through as text and entities it defines are not expanded, so a document that relies on them will be refused at the reference. Namespaces are treated as ordinary prefixed names. Encoding declarations are not honoured — the text you paste is already decoded by your browser. Nothing you enter leaves the browser; the same four anonymous usage counts as the rest of the site apply.