Diff Checker
Compare two texts side by side and instantly spot additions, deletions, and unchanged lines. Free, private, and runs entirely in your browser.
How to Use
- 1
Paste your original text in the left panel
- 2
Paste the modified text in the right panel
- 3
Click "Compare" to run the diff analysis
- 4
Review highlighted additions (green), deletions (red), and unchanged lines
Key Benefits
100% Private
All text comparison happens in your browser. Your content never leaves your device or gets uploaded to any server.
Line-by-Line Comparison
Uses an LCS-based diff algorithm for accurate line-by-line comparison with clear visual highlighting.
Detailed Statistics
See a summary of lines added, removed, and unchanged at a glance to understand the scope of changes.
Whitespace Options
Toggle whitespace-aware comparison to ignore or include trailing spaces and indentation differences.
Frequently Asked Questions
What diff algorithm does this tool use?
It uses a Longest Common Subsequence (LCS) based algorithm for line-by-line comparison, providing accurate results similar to professional diff tools.
Is my text uploaded to a server?
No. All comparison is performed entirely in your browser using JavaScript. Your text never leaves your device.
Can I ignore whitespace differences?
Yes. Toggle the "Ignore whitespace" option to skip differences caused by spaces, tabs, or trailing whitespace.
Is there a size limit for the text?
There is no hard limit, but very large files (over 50,000 lines) may cause slower performance since everything runs in the browser.
Can I swap the original and modified texts?
Yes. Use the "Swap" button to instantly switch the contents of the left and right panels.