XML Validator
Check that XML is well-formed and get the error code, line, and column, plus document stats when it passes.
Local workspace
Named projects in IndexedDB · Local only — never synced to our servers. Worksp…
Batch workspace
Format multiple files locally in one run.
Options
| Option | Description |
|---|---|
| Allow attributes without values | Accepts HTML-style attributes like <input disabled>. Strict XML requires every attribute to have a quoted value. |
FAQ
What's the difference between well-formed and valid XML?
Well-formed XML follows the syntax rules: one root element, matched and properly nested tags, and quoted attributes. Valid XML also conforms to a DTD or XSD schema. This tool checks well-formedness and doesn't load schemas.
Why does the validator show only one error at a time?
XML parsers stop at the first well-formedness error, because everything after it is ambiguous. Fix the reported line and validate again.
What does InvalidTag mean?
A closing tag doesn't match the most recently opened tag, or a tag is never closed. The message names both tags and where the open one started.
How do I fix 'Attribute is repeated'?
The element declares the same attribute twice. Keep one of them; XML doesn't allow duplicates, even with identical values.
Does the XML declaration have to come first?
Yes. <?xml version="1.0"?> must be the very first characters of the document, with no blank lines or spaces before it.