XML Validator Online
Validate your XML documents instantly in the browser. Check for well-formedness errors, unclosed tags, and syntax issues — all client-side with no data uploaded.
XML Formatter & Validator
Format, beautify, validate, and minify XML documents instantly. Supports comments, CDATA, processing instructions, and namespaces.
About XML Formatting
This tool formats XML documents for readability by adding proper indentation and placing each element on its own line. It validates your XML using the browser's built-in DOMParser before formatting.
Validation: Checks for well-formedness — properly nested tags, matching open/close tags, valid attribute syntax, and correct use of special characters. Reports the first error found.
Minify: Removes all unnecessary whitespace between tags and strips comments, producing compact single-line XML. Useful for reducing payload size in APIs and configuration files.
Supported features: XML declarations (<?xml?>), processing instructions, comments (<!-- -->), CDATA sections (<![CDATA[]]>), DOCTYPE declarations, namespaced elements, and self-closing tags.
What is XML validation?
XML validation checks whether a document follows the rules of well-formed XML. This includes verifying that every opening tag has a matching closing tag, attributes are properly quoted, elements are correctly nested, and special characters are properly escaped. A well-formed XML document can be parsed by any XML parser without errors.
Common use cases
Developers validate XML when troubleshooting parsing errors in API integrations, checking configuration files before deployment, or verifying XML exports from databases and CMS systems. It is also critical when building or consuming SOAP web services, processing RSS/Atom feeds, or working with XML-based data interchange formats.
Frequently Asked Questions
What is the difference between well-formed and valid XML?
Well-formed XML follows basic syntax rules (proper nesting, closed tags, quoted attributes). Valid XML additionally conforms to a specific schema (XSD or DTD). This tool checks for well-formedness, which is the fundamental requirement for any XML parser.
What are the most common XML errors?
The most common errors are unclosed tags, mismatched tag names, unescaped special characters (like & and <), missing quotes around attribute values, and incorrect nesting of elements.