How to Format and Validate XML

XML sits behind sitemaps, RSS feeds, configuration files and many older APIs. One mismatched tag and a parser refuses the whole file.

What the formatter does

Paste XML into the XML Formatter and it parses the document with your browser’s own XML parser. If it is well-formed, the tool re-indents it with two or four spaces, so <root><a>1</a><b><c>2</c></b></root> becomes a readable nested layout. If it is not, you get an “Invalid XML” message from the parser with the line and column, for example “error on line 1 at column 15: Opening and ending tag mismatch: a line 1 and b”. Text inside an element is placed on its own indented line.

What well-formed means

• There is exactly one root element.
• Every opening tag has a matching closing tag, in the right order: <a>1</b> is an error.
• Attribute values are in quotes.
• Special characters in text are escaped: & for an ampersand and < for a less-than sign.
• Tag names are case-sensitive, so <Item> and <item> differ.

Using the tool

1. Paste your XML.
2. Choose a two- or four-space indent.
3. Read the formatted output, or the error, and copy or download the result.

Well-formed is not the same as valid

The tool checks structure only. It does not check the document against a schema (XSD) or a DTD, so it cannot tell you whether the element names or order are what a given system expects. A sitemap can be well-formed and still be rejected by a search engine for a wrong field.

Careful with whitespace

Re-indenting adds whitespace between elements. In most data files that is harmless, but in documents where spaces inside text matter, check the result before replacing the original.

Frequently asked questions