XML Formatter / Validator

How this reads your output

The document is parsed before it is formatted, which is the important ordering: a mismatched or unclosed tag produces an error naming the problem rather than being silently reformatted into tidier nonsense. Once it parses, elements are indented by depth, with short text content kept on the line of its opening tag so a single-value element reads as one line rather than three.

What the results mean

Well-formed

Every element closes, in the right order, under exactly one root. This is the syntactic requirement all XML must meet.

Self-closing

Elements written with a trailing slash and no content. Equivalent to an empty pair of tags, and purely a style choice.

Declaration

The optional processing instruction at the top. Its main job is declaring the encoding when it is not UTF-8.

Common problems and fixes

A parser rejects a document that looks fine

Look for a bare ampersand first, since it must be written as & even inside text, and it is the most common cause. After that, check for a stray angle bracket in content, an attribute value without quotes, and a byte order mark before the declaration, which some parsers reject outright.

Special characters appear as question marks

The encoding declared in the XML declaration does not match how the file was actually saved. Declare UTF-8 and save as UTF-8. Note that if the two disagree, the declaration is what the parser believes, so an incorrectly declared file fails in ways that look like data corruption.

Frequently asked questions

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