BYTETOOLS

XML Validator

Free online XML validator and syntax checker: verify your XML is well-formed and read the parser's exact error, plus element and attribute counts. Private.

What is the XML Validator?

The ByteTools XML Validator checks whether a document is well-formed XML — every tag closed, properly nested, correctly quoted and with a single root element.

  • Strict well-formedness check with the browser's native parser
  • Shows the parser's exact error description
  • Valid documents summarized: root, elements, attributes, depth
  • Works with SOAP, RSS, Atom, SVG, sitemaps and config XML
  • Handles large documents quickly
  • 100% private — XML never leaves your browser

How to use the XML Validator

  1. 1

    Paste the XML document into the input box.

  2. 2

    Click Validate XML.

  3. 3

    If it is well-formed, review the root element, element count, attribute count and depth.

  4. 4

    If not, read the parser error to find the broken tag or character, fix it and re-validate.

About the XML Validator

The ByteTools XML Validator checks whether a document is well-formed XML — every tag closed, properly nested, correctly quoted and with a single root element. It uses the same strict XML parser built into your browser, so the verdict matches what real software will do with your file.

When the document is malformed you see the parser's own diagnostic message, which typically names the problem and where it occurred. When it is valid you get a quick profile: the root element name, total element count, attribute count and maximum nesting depth — handy for sanity-checking feeds, sitemaps, SVGs and API payloads.

Validation runs 100% locally in your browser. Nothing you paste is uploaded, logged or stored, making the tool safe for enterprise SOAP messages and private configuration files.

Frequently asked questions

How do I validate XML online?

Paste your document into this online XML validator and click Validate XML. It checks the markup with the browser's native parser and either confirms the document is well-formed or reports the exact error the parser hit, so you can find the broken tag fast.

Can I validate SOAP or check if my XML is well-formed?

Yes. A SOAP message is just XML, so paste the full envelope and the validator confirms whether it is well-formed — every tag closed, properly nested and correctly quoted — the same check any SOAP endpoint runs before it will accept your request.

What does well-formed XML mean?

Well-formed XML follows the core syntax rules: one root element, every open tag has a matching close tag, elements are properly nested, attribute values are quoted, and special characters like & and < are escaped. A document must be well-formed before any parser will read it.

What is the difference between well-formed and valid XML?

Well-formed means the syntax is correct; valid means the document also conforms to a schema such as a DTD or XSD that defines which elements and attributes are allowed. This tool checks well-formedness, which is what most day-to-day debugging needs.

Why do I get an 'unescaped ampersand' or 'not well-formed' error?

A bare & in text is interpreted as the start of an entity reference, so URLs like ?a=1&b=2 break the parse. Replace & with &amp; (and < with &lt;) inside text and attribute values, then re-validate.

Can XML have more than one root element?

No. A well-formed XML document must have exactly one root element that contains all the others. If you need to bundle several documents, wrap them in a common parent element.

Is my XML uploaded when I validate it?

No. The check runs entirely inside your browser using its built-in DOMParser. Your markup never touches a server, so confidential payloads and internal configuration files stay private.

Guides for XML Validator

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