Is the HTML diff checker free?

Yes, it's completely free with no registration required. All comparison is done locally in your browser.

What's the difference between HTML diff and plain text diff?

This tool is specifically optimized for HTML code with intelligent tag structure handling. It uses LCS (Longest Common Subsequence) algorithm for line-by-line comparison and can detect subtle attribute value changes.

Is my code uploaded to a server?

No. The diff algorithm runs entirely in your browser. Your code never leaves your computer. You can safely compare sensitive code.

How much code can I compare?

We recommend comparing up to 5000 lines or 100KB of code per session. Larger inputs may cause browser lag. For big files, consider splitting into chunks.

What do the colors represent?

Green background (+) = added content. Red background (-) = removed content. Yellow background = modified content. Line numbers are shown on the left for easy reference.

Free Online HTML Diff Checker

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Updated: 2026-07-11

📝 Enter HTML Code

Original (Old)

New (New)

How to Use

Paste the original HTML code in the left textarea
Paste the new HTML code in the right textarea
Click "Compare" to analyze differences
View highlighted additions (green), deletions (red), and changes (yellow)

Frequently Asked Questions

Q: How is HTML diff different from plain text diff?

HTML diff is optimized for HTML structure changes. This tool uses LCS (Longest Common Subsequence) algorithm for line-level diff detection, suitable for comparing HTML snippets, templates, and web page structural changes.

Q: How to read the diff results?

Results show side-by-side with line numbers. Green lines (+) = added content, Red lines (-) = removed content, Yellow lines = modified content. Line numbers help locate specific changes.

Q: Is my code secure?

Absolutely. All comparison happens in your browser. Your code is never uploaded to any server. Safe for sensitive code comparison.

Q: Does it support Chinese characters?

Yes. The Unicode-based comparison algorithm handles Chinese, Japanese, Korean, and all multi-byte characters correctly.

Q: Does this tool work offline?

Yes. Once loaded, this tool works entirely in your browser with no network requests. All processing is done client-side.

🔍 HTML Diff Checker

📝 Enter HTML Code

📊 Diff Results

How to Use

Frequently Asked Questions