What does the XML Formatter, Validator, and JSON Converter do?
Use this tool when you need a browser utility that validates and formats XML or converts structured values between XML and JSON. It accepts one well-formed XML document or a JSON object for JSON to XML mode and returns formatted or minified XML, or two-space-indented JSON. Results are deterministic for the same input except where cryptographic randomness, current time, or a live provider response is part of the task.
Formatting preserves meaning better than cross-format conversion
Use Format XML or Minify XML when XML remains the authoritative format. Use XML and JSON conversion for integration work where the chosen attribute and text-node representation is understood and exact lexical preservation is not required.
How do you use it?
- Choose Format XML, Minify XML, XML to JSON, or JSON to XML.
- Paste one complete document into Input and select Convert.
- Review the validated output, then copy or download it without uploading the source document.
Worked example
Format a compact XML document
Input
<project private="true"><name>KitLumi</name><tool>XML</tool></project>Output
<project private="true">
<name>KitLumi</name>
<tool>XML</tool>
</project>The formatter validates the document before rebuilding it with two-space indentation.
Common errors and fixes
| Symptom | Likely cause | Fix |
|---|---|---|
| The tool reports an invalid closing tag. | An element is missing its closing tag or the tag names do not match exactly. | Balance every start and end tag, including letter case, then run the conversion again. |
| A JSON round trip changes the shape of an element. | XML attributes, text nodes, repeated elements, and namespaces do not map one-to-one to ordinary JSON objects. | Use the generated JSON as an explicit representation and review @_ attribute keys and #text values before relying on a round trip. |
Important behavior of XML Formatter
XML and JSON have different data models, so namespaces, comments, mixed content, and repeated elements may not round-trip exactly.
Standards and implementation references
- W3C Extensible Markup Language (XML) 1.0 (opens in a new tab)Defines well-formed XML documents, elements, attributes, and character data.
- fast-xml-parser official repository (opens in a new tab)Documents the local parser, validator, and builder used by this page.
Frequently asked questions about XML Formatter
Does the XML Formatter upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the XML Formatter accept?
It accepts one well-formed XML document or a JSON object for JSON to XML mode. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the XML Formatter produce?
It produces formatted or minified XML, or two-space-indented JSON. Copy and download controls appear when the output format supports them.
What limitation should I know?
XML and JSON have different data models, so namespaces, comments, mixed content, and repeated elements may not round-trip exactly.
What changed?
Added XML formatting, XML validation, XML minification, XML and JSON conversion, responsive controls, explicit runtime disclosure, and task-specific examples and limitations.