XML Diff Comparator
指导
XML Diff Comparator
Compare two XML documents at the node level or the line level. The XML Diff Comparator highlights added, removed, modified, and attribute-level changes so you can spot exactly what changed without skimming through thousands of tags by eye.
Unlike plain text diff tools, this comparator understands XML structure: it ignores cosmetic whitespace, optionally skips comment nodes, and treats attribute sets as order-insensitive by default. The result is a diff that reflects real semantic change rather than reformatting noise.
如何使用
- Paste your original XML into the XML A box and the updated XML into the XML B box.
- 选择 Structural diff to see node-level changes grouped by add, remove, text, and attribute, or Line-level diff to see a unified view after pretty-printing.
- 切换 Ignore whitespace, Ignore comments，并且 Ignore attribute order depending on how strict you want the comparison to be.
- Copy the generated unified patch, or download it as a .patch file ready to drop into a code review.
特征
- Structural diff mode – Walks both documents as trees, pairing elements by tag name and reporting adds, removes, text changes, and attribute changes against an explicit XPath-like path.
- Line-level diff mode – Pretty-prints both documents with consistent indentation and runs a longest-common-subsequence (LCS) line diff to produce a familiar unified-diff view.
- Ignore noise toggles – Independent toggles for whitespace, comment nodes, and attribute order so cosmetic edits do not pollute the diff.
- Collapsible unchanged sections – In line mode, long runs of identical lines collapse to a single placeholder so the screen stays focused on the changes.
- Unified patch export – The exportable text always renders as a standard
@@ ... @@hunk format you can paste into a pull request or apply withpatch. - Auto-process – Diff recalculates as you type or change options; no submit button required.
常问问题
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What is the difference between a structural diff and a text diff for XML?
A text diff treats XML as a sequence of characters, so reformatting a tag onto multiple lines or reordering attributes appears as a change. A structural diff parses both documents into trees and compares nodes by their position and tag, then surfaces semantic differences such as added or removed elements, text changes, and attribute changes. For configuration files and data exchange, structural diffs are far less noisy.
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Why is the order of XML attributes generally not meaningful?
The XML specification declares that attribute order on a single element is not significant. Two elements with the same set of attribute names and values represent the same information regardless of the order in which they appear in the serialized markup. Most XML parsers, schema validators, and downstream consumers ignore attribute order, which is why diff tools usually offer a toggle to ignore order changes.
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How does the longest common subsequence algorithm produce a unified diff?
The longest common subsequence (LCS) algorithm finds the longest ordered sequence of items that appears in both inputs without changing the relative order. Lines that belong to the LCS are unchanged; lines from the first input that do not appear in the LCS are deletions, and lines from the second input that are not in the LCS are additions. Wrapping these classifications with location information and a few lines of context produces the standard unified diff format used by git and patch.
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Why does whitespace inside XML sometimes change meaning?
In most XML documents whitespace between elements is purely cosmetic, but certain document types treat whitespace as significant. XHTML, XSLT templates, and any element carrying an xml:space="preserve" attribute treat inner whitespace as part of the data. A safe default is to ignore whitespace when comparing structure, but to enable strict matching when working with whitespace-sensitive grammars.
