XML validator | Validate Your XML Instantly

Use our XML Validator to check your XML documents for well-formedness and syntax errors. Receive immediate feedback and detailed error messages for corrections. Ideal for developers and data professionals ensuring compliant XML files.


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Common XML Use Cases

Web Services & APIs: Validate SOAP messages and REST API responses

Data Exchange: Verify XML files before importing into databases or systems

Configuration Files: Check application config files for syntax errors

RSS/Atom Feeds: Validate news feeds and syndication formats

What Is an XML Validator?

An XML validator checks that your XML is well-formed — correctly nested tags, quoted attributes and a single root element — and highlights the line where any error occurs.

Rules for Well-Formed XML

RuleExample
One root element wraps everything<root>...</root>
Every tag must be closed<item>...</item>
Tags must nest correctly<a><b></b></a>
Attribute values are quotedid="1"
Tags are case-sensitive<Name> is not <name>

Well-formed XML follows these rules; a validator also checks validity against a schema (DTD or XSD).

Use this tool from your AI agent

Free JSON API and Model Context Protocol (MCP) server. No signup, no API key, CORS open. Designed for Claude, ChatGPT, Cursor, scripts and frontend apps. 

curl -X POST https://mate.tools/api/v1/xml-validate.php \
  -H "Content-Type: application/json" \
  -d '{"xml":"<?xml version=\"1.0\"?><root><a>1</a></root>"}'
import urllib.request, json

req = urllib.request.Request(
    "https://mate.tools/api/v1/xml-validate.php",
    data=json.dumps({"xml":"<?xml version=\"1.0\"?><root><a>1</a></root>"}).encode(),
    headers={"Content-Type": "application/json"},
)
with urllib.request.urlopen(req) as r:
    print(json.load(r))
const r = await fetch("https://mate.tools/api/v1/xml-validate.php", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({"xml":"<?xml version=\"1.0\"?><root><a>1</a></root>"}),
});
console.log(await r.json());

Add to claude_desktop_config.json (Claude Desktop), ~/.cursor/mcp.json (Cursor), or any other MCP-compatible client: 

{
  "mcpServers": {
    "mate-tools": {
      "command": "npx",
      "args": ["-y", "@mate-tools/mcp-server"]
    }
  }
}
API documentation OpenAPI 3.1 npm 60 req/min · 600 req/hour · 1 MB body cap

How to Use XML Validator

  1. Paste your XML content into the editor or drag & drop an XML file
  2. Click "Validate XML" to check for syntax errors and structure issues
  3. Use "Format XML" to beautify and properly indent your code
  4. Copy the validated XML or download it as a file

Frequently Asked Questions

Paste your XML content into the editor or drag and drop an XML file, then click Validate XML. The tool checks for syntax errors, missing tags, and improper nesting, and reports any issues with line numbers.

Validation checks if the XML follows correct syntax rules and reports errors. Formatting (beautifying) reorganizes the XML with proper indentation and line breaks to make it easier to read, without changing the content.

Yes, click Format XML to beautify your code with proper indentation, then use the Download button to save the formatted XML file or the Copy button to copy it to your clipboard.

What Is an XML Validator?

An XML validator checks that your XML is well-formed — correctly nested tags, quoted attributes and a single root element — and highlights the line where any error occurs.