HTML Diff & Compare
Compare two HTML documents and identify structural changes without treating formatting differences as meaningful changes.
How to compare HTML
- Paste the original in Document A.
- Paste the modified in Document B.
- Click Compare HTML.
What this HTML diff compares
- Elements, attributes, text.
- Comments and DOCTYPE.
- Script and style content.
- Child element order.
What differences are ignored
- Indentation and line breaks.
- Attribute order.
- Boolean attribute serialization.
- Void-element syntax.
- Class token order.
When HTML diff is useful
Comparing two HTML documents is useful whenever markup changes over time and you need to know exactly what was edited: reviewing revisions to a shared template, checking what a CMS actually changed after a content edit, or confirming what's different between two versions of a landing page before one replaces the other.
Structural and content differences vs. visual differences
This tool compares the two documents as parsed markup, not as rendered pixels. A change to an external stylesheet can make a page look completely different without changing a single tag, while a small markup change, such as a reordered element or an added class, might have no visible effect at all but still shows up here. Use this diff to find markup changes, and a visual review to find rendering changes.
Reading the diff results
Start with structural differences - elements added, removed, or moved - since those are most likely to affect layout or functionality. Attribute and text differences are usually smaller in impact but worth checking for accidental leftovers, like a debug class or placeholder text that shouldn't have shipped. If the result set feels larger than expected, an early structural change may be shifting how the rest of the document is matched.
Frequently asked questions
- Does this tool upload my HTML?
- No. Both documents are parsed and compared in your browser.
- Will a purely visual change, like new CSS, show up as a difference?
- No. This tool compares the two HTML documents you paste in, not how a stylesheet renders them, so a CSS-only change to colors, spacing, or layout won't appear unless the markup itself also changed.
- Is this a good way to review a CMS or template revision?
- Yes. Pasting the before and after HTML output of a page, email template, or landing page makes it easy to see exactly which elements, attributes, or text actually changed between the two versions, separate from any unrelated whitespace differences.
- Why doesn't reformatted HTML show as different?
- Indentation, line breaks, attribute order, and other formatting choices don't affect how a browser parses or renders the page, so this diff ignores them and focuses on differences that actually change the document.
- How should I read a large diff result?
- Look at structural changes first - added, removed, or reordered elements - since those are the most likely to affect layout or behavior. Attribute and text changes are usually lower-impact but worth a quick scan for anything unintentional, like a leftover placeholder or a mistyped class name.