Use the free XML Formatter and Validator below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Why XML Still Needs Formatting
XML is old, but it is far from dead. Config files, data feeds, office documents, Android layouts, and SOAP services all still use it. The problem is that XML produced by machines usually arrives on a single line, or with indentation that collapses after a copy and paste. Reading it feels like reading a paragraph with no spaces. Formatting restores the structure: each element on its own line, children indented under their parents, so the hierarchy is visible at a glance.
Validation is the other half. XML is strict. Every opening tag needs a matching closing tag, attribute values need quotes, and special characters like the less-than sign must be escaped. One slip breaks the whole document, and the program reading it will refuse to continue. Checking here first tells you exactly what is wrong before you feed the file to another system.
How to Use the Tool
Paste XML into the input box. Press Format XML for the indented version, Validate only for a verdict without output, or Minify to strip the extra whitespace back out for a compact file. Validation uses the fast-xml-parser validator, which reports the first error with its line and column. Formatting uses the browser’s own XML parser plus a careful printer, so the result is a faithful copy of your document with clean indentation.
Minify deserves a note. It removes whitespace between tags, which shrinks the file for transfer or storage. It does not remove whitespace inside text content, because that whitespace may be part of the data. A minified file is harder for humans to read, so keep your formatted copy for editing and use the minified copy only where size matters.
Common XML Errors and How to Fix Them
Mismatched tags are the classic error: an element opened as item and closed as items, or a closing tag forgotten entirely. The validator names the tag it expected, which usually points straight at the mistake. Unquoted attributes are next: an attribute written as id=1 instead of id=”1″ is invalid in XML, even though HTML tolerates it. Unescaped special characters are third: a raw & or < inside text breaks parsing, because XML reserves those characters for markup. Write & for an ampersand and < for a less-than sign.
Another common trap is the XML declaration. A file that starts with a declaration claiming one character encoding but saved in another will confuse some parsers. If you see encoding errors, check that the declaration matches how the file was actually saved, or remove the declaration and let the parser assume UTF-8.
Reading Formatted XML Well
Once formatted, read XML from the outside in. The root element wraps everything. Its children are the main sections, and their children are the details. If the nesting goes deeper than four or five levels, the design may be overcomplicated, and that is useful information too: deeply nested XML is hard to query and easy to break. Attributes are best for simple metadata, like an id or a type, while element text is best for content. If you see long paragraphs crammed into attributes, that is a smell worth noting.
Use formatting as a review step. Before you send an XML file to a colleague or a system, format it and skim it. You will spot a duplicated element, a wrong value, or a misplaced section far faster in indented form than in a single-line blob.
Frequently Asked Questions
Does formatting change my data? No. It only changes whitespace between tags. Element names, attributes, and text stay exactly the same.
Can it validate against a schema or DTD? No. It checks well-formedness: matching tags, quoted attributes, and legal characters. Schema validation, which checks whether the structure matches a contract, is a separate step.
Why did my XML declaration disappear from the output? The formatter prints the element tree, and the declaration is not an element. Your data is intact; add the declaration back if the receiving system requires it.
Paste your XML above, validate it, and make it readable again in one click.