XML Validator
Validate XML instantly in your browser — get a clear error if something's wrong (a mismatched tag, invalid syntax), or a formatted confirmation if it's well-formed.
What Is XML Validation?
"Well-formed" is XML's baseline requirement: every tag that opens must close, tags can't overlap, there's exactly one root element, and special characters like & and < must be escaped inside text content. A document can look mostly right and still fail one of these rules — a single unclosed tag makes the whole document unparseable.
Validation checks your XML against these well-formedness rules and tells you exactly what's wrong when it isn't — instead of leaving you to scan the whole document by eye for the one mismatched tag.
Why Validate XML?
Hand-edited XML (config files, RSS feeds, SOAP request bodies) is where well-formedness breaks most often — an unclosed tag, an unescaped & inside a URL, two root elements left over from a copy-paste. Validating before you use it catches these before they cause a confusing downstream parser failure.
How This Tool Works
This validator runs entirely in your browser. Paste your XML into the text area, click Validate, and see either a confirmed-valid, formatted result, or a clear description of what's wrong. Your data is never uploaded to any server — validation happens locally on your device.
Common XML Well-Formedness Mistakes
| Mistake | Example (invalid) | Fix |
|---|---|---|
| Unclosed tag | <name>Alice</root> | Every opened tag needs a matching close: <name>Alice</name> |
| Mismatched tags | <a><b></a></b> | Tags must close in the reverse order they opened |
| Multiple root elements | <a>1</a><b>2</b> | Wrap them in a single root: <root><a>1</a><b>2</b></root> |
| Unescaped special characters | <note>Tom & Jerry</note> | Escape & as & (also < as <) |
| Unquoted attribute values | <item id=42> | Attribute values need quotes: <item id="42"> |
Well-Formed vs. Schema-Valid
Well-formed means the XML syntax itself is correct — matched tags, one root, proper escaping. It doesn't mean the document matches a particular structure a system expects (that's what an XSD or DTD schema checks separately). This tool checks well-formedness, which is the first thing that has to be true before schema validation is even possible.
Common Scenarios for Validating XML
Checking a Hand-Edited Config File
Spring, Maven, and Android config files are all XML, and hand-editing them is where unclosed tags and stray characters sneak in. Validating before you build or deploy catches the mistake immediately instead of chasing a confusing parser error later.
Debugging a SOAP or XML API Error
When a SOAP service rejects a request with a generic parsing failure, pasting the request body here confirms whether the problem is malformed XML at all, or something else in your request logic.
Verifying a Generated RSS or Atom Feed
Feeds generated by a script or CMS plugin can silently break well-formedness — an unescaped ampersand in a post title is a classic cause. Validating the feed output catches it before subscribers' readers start failing to parse it.
Reviewing a Config File Before Committing
Files edited or merged by hand can end up with duplicated root elements or a tag closed in the wrong order. Validating before committing catches it before it breaks whatever consumes the file downstream.
Confirming XML From an Untrusted Source
Before feeding XML from an external API or file upload into your own tooling, confirming it's well-formed first avoids passing broken data further down your pipeline. Once your reference doc validates, our PDF to DOCX converter is useful if you need to turn a companion PDF into something editable.
Other Ways to Validate XML
You can also validate XML using a command-line tool like xmllint --noout, or the W3C's online XML Validator. FileCast is useful when you don't have either installed.
Frequently Asked Questions
Is it safe to validate my data here?
Yes. This tool processes your data entirely in your browser. Nothing is uploaded to any server — validation happens locally on your device. No one else can see or access your data during or after validation.
What exactly does "well-formed" mean?
It means your XML follows the basic structural rules: every tag closes, tags nest properly without overlapping, there's exactly one root element, and special characters are escaped. It doesn't check the document against a specific schema (XSD/DTD) — see the next question.
Does this validate against an XSD or DTD schema?
No. Schema validation checks that your XML matches a specific structure (which elements are allowed where, what data types are expected) defined in a separate XSD or DTD file. This tool checks well-formedness only — the baseline syntax check that has to pass before schema validation is even possible.
What does the error message tell me?
It describes the specific well-formedness problem the parser hit, such as a mismatched or unclosed tag. For very short inputs the description can be terse, but it always points at the actual structural issue rather than a generic "parse failed."
Can I validate multiple files at once?
This tool validates one input at a time. Paste your XML, check the result, and repeat for additional files.