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XML Editor Online

Edit, validate, format, and minify XML in your browser. Real-time syntax validation with error line detection, pretty-print with configurable indent, and minification.

Last updated: May 28, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution
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What is XML Editor Online?

An online XML editor that lets you edit, validate, format, and minify XML directly in your browser without installing any software. Paste or type your XML, and the tool validates it in real time as you type — reporting any syntax errors along with the line number where the problem occurs.

You can use the Format button to pretty-print messy or minified XML with consistent indentation, making it much easier to read and navigate. The Minify button strips all whitespace between tags, producing the most compact representation. Both operations validate the XML first, so you always know the output is well-formed.

How to Use XML Editor Online

1

Paste your XML into the editor area on the left

2

The validation status indicator updates instantly as you type

3

If the XML is invalid, the error message and line number appear below the editor

4

Click "Format" to pretty-print the XML with the selected indentation

5

Click "Minify" to strip all unnecessary whitespace

6

Adjust "Indent" (2 or 4) and toggle the XML declaration as needed

7

Copy or download the formatted output from the right panel

Common Use Cases

  • Validating XML configuration files before deploying to production
  • Formatting minified or one-line XML responses from APIs to make them readable
  • Checking XML syntax when authoring SOAP requests, Ant build files, or Maven POM files
  • Cleaning up messy XML data before importing it into a database
  • Minifying XML responses for embedding in code or reducing file size
  • Quickly checking element counts and nesting depth of XML documents

Example Input and Output

Messy one-line XML formatted with 2-space indent:

Input XML (unformatted)
<config><database host="localhost" port="5432"><name>myapp</name><user>admin</user><pool maxSize="10" minSize="2"/></database><cache ttl="3600" enabled="true"/></config>
Formatted XML
<?xml version="1.0" encoding="UTF-8"?>
<config>
  <database host="localhost" port="5432">
    <name>myapp</name>
    <user>admin</user>
    <pool maxSize="10" minSize="2"/>
  </database>
  <cache ttl="3600" enabled="true"/>
</config>

How This Tool Works

XML is parsed and validated using the browser's native DOMParser with the application/xml MIME type. The parser reports well-formedness errors including line numbers. A custom recursive serialiser re-serialises the parsed DOM tree with configurable indentation, producing consistent formatted output. Minification uses XMLSerializer followed by whitespace removal. All operations run synchronously in the browser.

Technical Stack

Browser DOMParser APIBrowser XMLSerializerCustom recursive XML serialiserClient-side only

Privacy First

XML editing and validation runs entirely in your browser. Your XML data — which may contain configuration secrets, API keys, or sensitive business data — is never transmitted to our servers.

Frequently Asked Questions

What XML errors does the validator detect?

The validator uses the browser's native DOMParser which detects all well-formedness errors: unclosed tags, mismatched tags, missing root element, multiple root elements, unescaped special characters (&, <, >), invalid characters in tag names, and malformed attribute values. DTD and schema validation (XSD) is not currently supported.

How does the error line number work?

When the browser's XML parser detects an error, it reports the location in its error message. The tool extracts the line number from that message and displays it prominently so you can jump directly to the problem. The exact format depends on the browser's XML parser implementation.

Does formatting change my XML data?

No. Formatting only adds or removes whitespace between tags to improve readability. The element structure, attribute values, and text content are preserved exactly. However, whitespace-only text nodes between elements (pure indentation whitespace) may be normalised.

What does minification do?

Minification strips all whitespace between XML tags, producing a single-line or very compact version of the document. This reduces file size and is useful for network transmission, embedding XML in JSON strings, or fitting XML into single-line fields. The XML remains fully valid and parseable.

Can I use this to edit large XML files?

Yes, but browser performance may degrade for very large files (several megabytes) since all processing runs in the JavaScript engine. For files larger than ~5MB, a desktop XML editor may be more responsive. For typical config files, API responses, and XML data files, browser processing is fast.

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