XML Formatter & Validator

Well-formed means the XML follows the basic syntax rules every XML document must follow: every tag is closed, tags are properly nested, there's exactly one root element, and attribute values are quoted. This tool checks well-formedness — it does not check "validity" in the stricter sense of conforming to a schema or DTD (a set of rules for which elements and attributes a specific document type is allowed to have). Well-formed XML can still be invalid against a particular schema; this tool has no way to know what schema, if any, your XML is meant to follow, so it doesn't attempt that check.

The most common ones: an unclosed tag (<title>Book), mismatched opening and closing tags (<title>...</name>), more than one root element, and invalid characters like a bare & or < inside text content that should have been escaped as &amp; or &lt;. Each error is reported with the line and column where the parser gave up, when the browser's parser provides one.

Formatting re-indents the structure and normalizes whitespace BETWEEN tags — the insignificant whitespace that exists purely for human readability, which is what makes a formatter useful in the first place. It does not change element names, attribute values, or actual text content, and it preserves an XML declaration (<?xml version="1.0"...?>) if your input has one, rather than dropping it.

No. Parsing, validation, formatting, and minification all happen locally in your browser using native Web APIs — nothing is uploaded, logged, or transmitted.