XML Line Numbers Viewer
A read-only view of pasted XML with a synchronised line-number gutter, for referencing errors.
What is Line Numbers?
A lightweight viewer with a line-number gutter. Its job is small and concrete: when a validator, a log or a colleague cites a line number, this shows you that line without an editor fighting you over indentation.
How it works
The text is split into lines and each is rendered with its number, so the gutter scrolls and wraps with the content rather than drifting out of sync the way a separate pane does. Line endings are normalised for display and reported, tab width is configurable, and the panel stays monospaced so a column number from an error message actually lines up.
- Paste the document. Drop in XML, a schema, a feed or an XPath expression. Everything is parsed in the page: no upload, no server round trip, and the tools keep working with the network switched off.
- Set the options that match your document. Indent unit, whether to keep comments, which dialect, which output method. The defaults are the safe ones — nothing that changes meaning is enabled for you.
- Read the result, then copy or download it. Results appear as you type, copy straight to the clipboard, and download with a sensible filename (.xml, .xsd, .csv). Reset returns every field to its default.
Examples
A minified document from an API response
Paste one line of XML and the Formatter indents it, wraps long start tags one attribute per line and normalises empty elements — without touching text inside mixed content.
An XPath that works in Chrome and not in your servlet
The XPath Tester evaluates against a real tree and reports the axis or function it cannot support, instead of returning zero nodes and letting you guess why.
A document that will not parse
The Validator gives line and column for every mismatched tag, stray ampersand and duplicate attribute, with the reason in words: which open element was expected, which was found.
A schema that only half matches your data
The XSD Validator marks each violation with the path of the offending node, and the Schema Generator goes the other way — inferring a starting-point XSD from real documents.
Common mistakes
Assuming a pretty-printer cannot change meaning
Whitespace between elements is often insignificant, but inside mixed content it is not: `<p>Hello <b>world</b></p>` must stay on one line. Formatting here re-indents element-only content and leaves mixed content alone.
Treating a validation pass as proof of interoperability
The DTD and XSD validators implement honest subsets. A document reported valid here can still be rejected by a full validator that understands identity constraints, substitution groups or XSD 1.1 assertions — each page lists what it does not cover.
Reading the whole document because the parser did
A DOCTYPE is not inert. If your parser resolves external entities, pasting an untrusted document is enough to read a file or call an internal URL. The XXE Risk Checker shows what a document asks for; the fix is in the parser configuration.
Forgetting that attributes and elements are not interchangeable
`<id>1</id>` and `id="1"` mean different things to every schema and every XPath. When converting to CSV or YAML the distinction is preserved (`@id`), because flattening it away is the change that costs an afternoon later.
Frequently asked questions
Why do the line numbers in my error message not match?
Line numbering usually starts at the prolog, but a BOM or a stripped first line shifts everything by one. The viewer reports whether a BOM was present and how many lines were found, so you can tell which of the two counts the parser is using.
Can I edit the document here?
No, deliberately. This is the reference view you compare against while the editable copy lives in the tool that produced the error message. Two editable panes and one line number is how mistakes get made.
Does it handle very large documents?
It renders what the browser can lay out comfortably — tens of thousands of lines. Beyond that, a desktop editor is the right tool; the point here is a shared reference for a document somebody pasted into a chat.