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XML Studio
Check well-formed XML and validate against an XSD schema.
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Output initialises when this pane is visible.
Check that XML is well-formed and optionally conforms to a schema.
XML validation confirms a document is syntactically correct (well-formed) and, when you supply a schema, that its structure matches expected rules (valid). Well-formedness catches unclosed tags, illegal characters, and namespace errors before they break parsers in production.
XSD (XML Schema Definition) validation goes further — enforcing element order, data types, and required fields. This is common in B2B integrations where partners exchange strictly typed messages.
This validator runs locally in your browser. Read XML well-formedness and XSD validation for examples and troubleshooting tips.
Step-by-step guide for XML Validator. Everything runs locally in your browser.
Load an XSD file or paste a schema, then run validation against your document. Errors list the XPath-like path and constraint that failed.
Edit XML in the input pane and validation refreshes automatically. Use suggested fixes when offered, then re-run XSD validation after structural changes.
Need tree view, schema validation, or other modes? Open XML Editor Pro for the full guide with Diff examples and workflows.
What this XML Validator page offers — processed locally in your browser.
Instant parse errors with line and column pointers.
Validate structure when you provide an XML Schema.
All processing runs in your browser. Nothing is uploaded.
Common questions about XML Validator.
Yes. Parsing, formatting, diffing, validation, XPath, transforms, and XSLT all run inside your browser.
Data is not sent to a server. The only local storage is your session in localStorage, which
you can clear in browser settings.
After the first visit (when Monaco and assets are cached), you can edit, format, diff, and transform without a network connection. “Load from URL” still needs network access and a CORS-friendly server.
Auto-fix handles many well-formedness problems: unclosed or mismatched tags, duplicate attributes,
unquoted attribute values, bare & in text, broken comments and CDATA sections, and orphan
closing tags. It appears in the status bar when parsing fails and inside Validate mode with per-error fix
buttons. Auto-fix does not change XSD-valid content — it only makes XML syntactically parseable so you can
continue editing or run schema validation.
Yes. Open Diff mode (Ctrl/⌘+D), paste the second file on side B, and keep Sort enabled on both sides. Sibling elements are reordered using a stable canonical ordering so equivalent documents align. Turn Sort off when sequence matters (e.g. ordered event lists).
Quick try: load the sample catalog, open Diff, paste the same XML on B but swap the two
<book> blocks. With Sort on, the diff should be empty; with Sort off, you will see the
blocks highlighted as changed lines.
Those options rebuild the view from your source text: Sort reorders elements; Ignore WS normalises whitespace in text nodes and tells the diff engine to ignore leading/trailing spaces on each line. Your stored source is kept separately so toggling options updates the display without losing the original unless you edit the diff pane itself.
When Sort or Ignore WS is on, the file is parsed with
DOMParser and comments are not preserved in the diff view. For comment-sensitive compares,
turn both off on that side — Format/Minify still work on the raw text.
XPath 1.0 (browser document.evaluate). Unprefixed names match local element names; the
sample catalog avoids a default namespace so paths like /catalog/book/title work as
expected.
JSON, YAML, CSV, Markdown, and HTML table. Pick a target in Transform mode and click Convert. Conversion uses the browser DOM — very large documents may take a moment.