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XML Validator

Check whether XML is well-formed in your browser, with the parser’s line and column for the first problem it finds.

Paste XML

Verdict

Paste XML and validate to see the verdict here.

Your file is never sent to a server. It is read and processed by your own browser, and the results are not stored.

How to use it

  1. Paste the XML, or choose a file.
  2. Validate and read the verdict.
  3. Fix the reported line, then validate again until it passes.

Limits worth knowing

  • Well-formedness only; XSD or DTD schema validation is out of scope.
  • External entities are never resolved, by design.
  • The report names the first error found, not every possible error.
  • Files above 10 MB are refused to keep the tab responsive.

Well-formedness is the parser’s contract

An XML parser does not forgive: one bad byte and it stops. Well-formedness is the set of rules it needs to even begin — a single root, balanced tags, quoted attributes, escaped markup characters. This tool tells you whether that contract is met, and if not, where the first breach is.

Anything beyond that — whether the document matches your company’s schema — requires the schema itself, which this tool does not have and does not fetch.

Common first errors

Unescaped ampersands in text, copied smart quotes inside attributes, a stray   the file did not define, and tags closed out of order head the list. The reported position is where the parser noticed, which is usually the offending byte.

Frequently asked questions

Does XML Validator upload my files to any server?

No. XML Validator runs in your browser, and the file is read there rather than sent to a server for processing. Our host still sees ordinary page-request metadata, which is described on the privacy page.

Is XML Validator free to use?

Yes, XML Validator is free, with no paid tier, no account, and no watermark added to your output. The limits are technical rather than commercial: file size, page count and supported formats are listed on this page.

What file formats and sizes are supported?

XML Validator supports .xml, .svg, .xaml, .xsd, .xsl, .txt files up to 10MB directly in your browser.

Does it validate against a schema?

No. It checks well-formedness, which is what XML parsers require. XSD schema validation is a different problem and this tool does not pretend to do it.

Where exactly will I see an error?

The validator reports the line and column of the first problem it can locate — typically an unclosed tag, a stray angle bracket, or a mismatched name. Everything before that point parsed fine.

Are external DTDs fetched?

Never. The validator operates on the document text only and never fetches a URL, so a crafted SYSTEM reference cannot be used to probe your network or internal services.

What counts as “well-formed”?

One root element, properly nested and closed tags, quoted attribute values, escaped & and <, and legal comment and processing-instruction syntax.