XML Formatter & Validator

The SolversPro XML Formatter & Validator is a free browser-based developer utility that validates, beautifies, minifies, and inspects XML document hierarchies client-side with zero server uploads.

Input Data

<?xml version="1.0" encoding="UTF-8"?>
<catalog>
  <book id="bk101">
    <author>Gambardella, Matthew</author>
    <title>XML Developer's Guide</title>
  </book>
</catalog>

XML Well-Formedness Rules & Entity Specifications (W3C XML 1.0)

Core syntactic constraints and predefined character entity references required for valid XML parsing.

XML Standard Rule Well-Formed Syntax Entity Escape Code Common Validation Error
Single Root Element <root><child/></root> N/A Multiple unparented sibling root tags
Closing Tags Required <tag>content</tag> or <tag/> N/A Omitting self-closing slash (<br>)
Case-Sensitive Tags <User></User> N/A Mismatched casing (<User></user>)
Quoted Attributes <item id="101"> N/A Unquoted attribute values (<item id=101>)
Ampersand Entity AT&amp;T &amp; Raw unescaped & character
Less-Than Entity 5 &lt; 10 &lt; Raw unescaped < symbol in text node

Frequently Asked Questions

What constitutes a 'well-formed' XML document?

A well-formed XML document strictly adheres to W3C XML syntax rules: exactly one root element, matching opening and closing tags, correctly nested elements, quoted attribute values, and properly escaped entity references.

Is my XML markup sent to an external server for processing?

No. All XML parsing, DOM validation, formatting, and tree generation execute entirely inside your local browser via the native DOMParser API. No data is sent across the network.

Can this tool handle XML with CDATA sections and namespaces?

Yes. The parser recognizes XML namespaces (xmlns), CDATA unparsed character blocks, processing instructions, and standard XML declaration prologues.