What is XML formatting?
XML (eXtensible Markup Language) is a text format for structured data used in configuration files, APIs, web services, and data exchange between systems. Raw XML is often written as a single line or with inconsistent indentation, making it hard to read and debug.
XML formatting — also called pretty printing or beautifying — adds consistent indentation and line breaks so the document's structure is immediately visible. A well-formatted XML file lets you scan parent-child relationships at a glance, spot missing closing tags, and understand deeply nested structures without squinting at a wall of angle brackets.
This tool uses your browser's built-in XML parser to format your document — no server upload required, and your data never leaves your machine.
Format vs Minify
**Formatting** expands XML with indentation and newlines. Use it when: - Debugging an API response that arrived as a single compressed line - Reviewing a config file someone wrote without indentation - Sharing XML with colleagues who need to read it - Checking the structure of a document before processing it
**Minifying** removes all unnecessary whitespace between tags, making the file as compact as possible. Use it when: - Deploying XML config files to production where size matters - Sending XML payloads over a network API - Storing XML in a database and minimizing storage footprint - Reducing bandwidth for XML-based web services
Minified XML is functionally identical to formatted XML — the data and structure are preserved, only whitespace is changed.
Why validate XML?
XML has strict rules. Unlike HTML, which browsers forgive for sloppy syntax, XML parsers reject any document that is not well-formed. A single missing closing tag or mismatched quote breaks the entire document.
Validating before use catches errors early. Common scenarios where validation saves time: - Before sending XML to an API that will reject malformed requests - After manually editing a config file to catch typos - When receiving XML from a third party that may not follow the spec - Before importing XML data into a database or application
This tool checks well-formedness: proper nesting, matching tags, valid attribute syntax, and correct XML declaration. It reports the exact error and approximate location so you can fix it quickly.
Common XML errors
**Unclosed tags** — Every opening tag needs a matching closing tag, or the tag must be self-closing. An item tag must be followed by a matching closing tag or written as a self-closing element.
**Mismatched tags** — Tag names are case-sensitive. A Book opening tag and a book closing tag do not match.
**Unescaped special characters** — The characters less-than, greater-than, ampersand, double-quote, and single-quote must be escaped as their entity references when used in text content or attribute values.
**Multiple root elements** — XML documents must have exactly one root element. Having two top-level tags at the same level is invalid.
**Invalid attribute format** — Attribute values must be quoted. An unquoted attribute value is invalid.
**Invalid XML declaration** — If present, the XML declaration must be the very first line with no whitespace before it.
How to use
1. Paste your XML into the input area, or click "Load Sample" to try a sample document. 2. Choose a mode: "Format" to pretty print with indentation, or "Minify" to compress. 3. If formatting, choose your preferred indent style: 2 spaces, 4 spaces, or a tab character. 4. Click "Format XML" or "Minify XML" to process the document. 5. If the XML is valid, the result appears below along with size comparison stats. 6. Click "Copy" to copy the result to your clipboard. 7. To check validity without transforming, click "Validate Only."
FAQs
Q: Is my data safe? A: Yes. All processing happens entirely in your browser using the built-in DOMParser API. Your XML is never sent to any server.
Q: What's the difference between XML and HTML? A: Both use angle-bracket tags, but XML is stricter. HTML allows unclosed tags and is case-insensitive; XML requires every tag to be closed and is case-sensitive. HTML has a fixed set of tags defined by the spec; XML lets you define your own tags for any purpose.
Q: Why does my XML fail validation? A: The most common causes are unclosed tags, mismatched case in tag names, unescaped special characters like ampersand or less-than in text content, or multiple root elements. The error message shown by this tool will point to the specific problem.
Q: Does this tool support XML namespaces? A: Yes. The browser's built-in XML parser handles namespaces correctly. Namespace prefixes and xmlns declarations are preserved in both formatted and minified output.
Q: What encoding does this tool support? A: The tool works with UTF-8 text, which covers the vast majority of XML documents. If your XML has a different encoding declared in the XML declaration, be aware that the browser may handle it differently depending on how the text was pasted.
Q: Can I use this for large XML files? A: Yes, for most practical sizes. Since processing happens in your browser, very large files (tens of megabytes) may cause a brief pause. For extremely large files, a server-side tool may be more appropriate.
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