XML Diff

About this tool

XML Diff compares two XML documents by structure, not by text lines. A line-based diff flags every re-indentation and every reordered attribute; this one parses both documents into element trees and reports only the differences that actually change the data.

Paste your first (left / old) document and your second (right / new) document. The tool walks both trees in parallel:

• Elements are matched child by child, using the sibling-matching strategy you choose.
• Attributes are compared as a sorted map, so attribute order never matters.
• Text is whitespace-normalized by default, so indentation and line breaks never matter. CDATA is folded into the element's text, so <a><![CDATA[hi]]></a> equals <a>hi</a>.
• Every difference is reported with an XPath-style path — /catalog/book[2] for an element, /catalog/book[2]/@id for an attribute, /catalog/book[2]/title/text() for text — and classified as added, removed or changed.

Worked example

Comparing

<catalog><book id="1"><title>Rust</title></book></catalog>

with

<catalog><book id="2"><title>Rust 2</title></book></catalog>

gives this report (JSON format, indent 2):

{
  "equal": false,
  "added": 0,
  "removed": 0,
  "changed": 2,
  "changes": [
    { "path": "/catalog/book/@id", "kind": "changed", "old": "1", "new": "2" },
    { "path": "/catalog/book/title/text()", "kind": "changed", "old": "Rust", "new": "Rust 2" }
  ]
}

The same comparison with Report format = text gives:

2 differences: 0 added, 0 removed, 2 changed
~ /catalog/book/@id  1 -> 2
~ /catalog/book/title/text()  Rust -> Rust 2

Options

• Sibling matching — Smart alignment (default) aligns identical subtrees first, so inserting one element in the middle is reported as a single addition instead of shifting every later sibling. By position compares siblings strictly index by index. Ignore order treats siblings as a set, so a reordered document compares as equal.
• Ignore insignificant whitespace (on by default) collapses whitespace runs and drops whitespace-only text nodes. Turn it off for an exact text comparison.
• Ignore comments (on by default). Turn it off and comment changes appear as comment() nodes.
• Ignore namespace prefixes makes ns:book and p:book match and drops xmlns declarations from the comparison.
• Compare numbers numerically makes 1 equal 1.0 and 2.50 equal 2.5 in both text and attribute values.
• JSON indent sets the output indentation (0 minifies); it is ignored for the text report.

Everything runs locally in your browser via WebAssembly — your documents are never uploaded.

Limits and edge cases

• Each document is limited to 1 MB and 500 nesting levels; larger input is rejected with a clear error naming the side that failed.
• Mixed content: an element's direct text nodes are folded into one value, so moving text around between sibling elements inside the same parent is not reported positionally.
• The XML declaration, DOCTYPE and processing instructions are not compared.
• Custom DTD-defined entities are compared as written when they cannot be resolved.

Handy for

• Reviewing changes between two config, POM, SOAP or feed versions.
• Checking that a re-serialized document is semantically unchanged.
• Producing a machine-readable change report for tests, CI or audits.

FAQ