Diff Checker
Compare two pieces of text and see the differences highlighted line by line. Free, browser-based text diff tool. No data sent to servers.
How to Use
- Paste your original text into the Original panel.
- Paste your modified text into the Modified panel.
- Click Compare to see the diff.
- Lines highlighted in red were removed; lines in green were added.
- Use Swap to reverse the comparison direction.
About This Tool
This diff checker performs line-by-line comparison using the Longest Common Subsequence (LCS) algorithm —
the same principle used by git diff and Unix diff. It's ideal for comparing
code, configuration files, log output, or any text where line-level changes matter.
FAQ
Is my text sent to any server?
No. All diff computation runs entirely in your browser. Your text never leaves your machine.
What diffing algorithm does this use?
This tool uses a line-level Longest Common Subsequence (LCS) algorithm — the same principle used by Unix diff.
Can I compare code files?
Yes. Paste any plain text — source code, config files, prose — and this tool will show added and removed lines.
Are whitespace-only differences shown?
Yes. By default all differences are shown, including lines that differ only in whitespace.