XML Formatter — Beautify & Validate XML Online

Clean, indent, validate and convert XML. Fast, private, mobile-friendly.

Free • No signup
Client-side

What this tool does

The XML Formatter tidies up XML with consistent indentation, checks it for well-formedness, and optionally converts XML to JSON — all in your browser (no server upload).








What Is XML and Why Does It Need Formatting?

XML (eXtensible Markup Language) is a text-based format for storing and transporting structured data. Unlike HTML — which is designed specifically for displaying web content — XML is a general-purpose markup language designed to carry data in a way that is both human-readable and machine-readable. It uses custom tags defined by the application or developer rather than a fixed set of predefined tags.

A simple XML document looks like this when properly formatted:

xml

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book category="fiction">
    <title>The Great Gatsby</title>
    <author>F. Scott Fitzgerald</author>
    <year>1925</year>
    <price>12.99</price>
  </book>
  <book category="non-fiction">
    <title>Thinking, Fast and Slow</title>
    <author>Daniel Kahneman</author>
    <year>2011</year>
    <price>16.50</price>
  </book>
</bookstore>

The same data received from an API or exported from a system often looks like this:

xml

<?xml version="1.0" encoding="UTF-8"?><bookstore><book category="fiction"><title>The Great Gatsby</title><author>F. Scott Fitzgerald</author><year>1925</year><price>12.99</price></book></bookstore>

Both are functionally identical to a machine. But the first is readable in seconds while the second requires careful parsing to understand. This tool converts the second form into the first — instantly.

XML vs JSON vs HTML — Understanding the Differences

XML is often compared to JSON and HTML because all three are text-based formats used in web and software development. Understanding the distinctions helps you know when you’ll encounter XML and why tools for working with it matter.

FeatureXMLJSONHTML
Primary purposeData storage and transportData exchangeWeb page structure
Tag structureCustom tags defined by userKey-value pairsFixed predefined tags
ReadabilityModerateHighModerate
VerbosityHighLowModerate
Supports attributesYesNoYes
Schema validationXSD, DTDJSON SchemaHTML validators
Common use casesConfig files, SOAP APIs, RSSREST APIs, JavaScriptWeb pages

XML is still heavily used despite JSON’s rise in several contexts: SOAP web services in enterprise systems, Android app configuration (AndroidManifest.xml), Maven and Gradle build files, Microsoft Office document formats (DOCX, XLSX are zipped XML), RSS and Atom feeds, SVG graphics files, and many legacy enterprise integration systems.

Common XML Errors and How to Fix Them

XML is stricter than HTML — browsers are forgiving of malformed HTML, but XML parsers reject documents with any syntax error. Understanding the most common errors saves debugging time.

Unclosed tags — Every opening tag in XML must have a matching closing tag. <name>John</name> is valid. <name>John without a closing tag causes a parse error. Self-closing tags like <br /> are also valid for elements with no content.

Mismatched tags — Tags must be properly nested. <outer><inner></outer></inner> is invalid because the inner tag closes after the outer tag. The correct structure is <outer><inner></inner></outer>.

Invalid characters in tag names — XML tag names must start with a letter or underscore and can contain letters, digits, hyphens, underscores, and periods. Tag names cannot start with a number or contain spaces. <first-name> is valid. <first name> and <1stname> are not.

Unescaped special characters — The characters <, >, &, ', and " have special meaning in XML and must be escaped when used as data content. <price>10 < 20</price> is invalid. The correct form uses &lt; for < and &amp; for &.

Missing XML declaration — While technically optional, the XML declaration <?xml version="1.0" encoding="UTF-8"?> at the top of a document is strongly recommended as it specifies the version and character encoding.

The Validate button in this tool uses the browser’s built-in XML parser to check well-formedness and report the exact line and character position of any errors found.

Real-World Situations Where XML Formatting Matters

API debugging — SOAP APIs and many enterprise web services return XML responses. When debugging an integration, pasting a minified XML response into this formatter instantly makes the data structure visible, saving significant time over reading a single-line blob.

Configuration file editing — Android developers regularly work with AndroidManifest.xml, res/values/strings.xml, and other configuration files. Maven developers work with pom.xml. Properly formatted files are easier to edit, diff, and review in pull requests.

RSS and Atom feed maintenance — Blogs and news sites publish RSS feeds as XML. Validating and formatting your feed file ensures subscribers and feed readers receive correctly structured data without parse errors.

Data migration — When migrating data between systems, XML is a common intermediate format. Formatting and validating the XML before import helps catch structural errors early rather than debugging failed imports.

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