How it works
How to use the XML Validator
Paste XML
Or drop a file onto the editor.
Read the report
Errors are underlined in the editor with a clear message.
Fix and re-check
Validation re-runs as you type.
Common XML errors
- Unclosed or mismatched tags (
<a><b></a>) - Unescaped
&or<in text - Unquoted attribute values
- More than one root element
- Text before the XML declaration
Built for developers
Why developers use it
Private by design
Runs 100% in your browser. Nothing you paste is uploaded, logged or stored on a server.
Instant results
Output updates as you type, with precise error locations when something is wrong.
Works offline
Once loaded, the tool keeps working without a connection. Install it as an app if you like.
Free, no sign-up
No accounts, no limits, no watermarks.
FAQ
Frequently asked questions
What does well-formed mean?
That the document follows XML syntax rules. Schema validation (XSD/DTD) is a separate, stricter check.
Is my data uploaded anywhere?
No. Everything runs locally in your browser — nothing you paste or open is sent to a server, logged or stored. The tool keeps working offline once the page has loaded.
Keep going
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