How does the diff checker work?

Paste your original text on the left and the changed text on the right, then click Compare. The tool aligns the two texts line by line using a longest-common-subsequence algorithm and highlights every added, removed, and unchanged line.

Is my text private and secure?

Yes. All comparison happens entirely in your browser. Your text is never uploaded to any server or stored anywhere. Close the tab and your data is gone.

What do the colors mean?

Green lines with a plus sign were added in the changed text, red lines with a minus sign were removed from the original, and neutral lines are unchanged between the two versions.

Can I ignore whitespace or letter case?

Yes. Enable the 'Ignore whitespace' option to treat lines that differ only in spacing as identical, and enable 'Ignore case' to treat uppercase and lowercase letters as the same when comparing.

Diff Checker

Compare two texts and instantly highlight added and removed lines side by side.

Ignore whitespaceIgnore case

Original

Changed

Differences

+0 additions-0 deletions

Enter text in both fields to see the differences.

How to Use

Spot every change between two texts in seconds.

Paste Both Texts

Enter the original version on the left and the changed version on the right.

Compare Lines

The tool aligns both texts line by line and highlights every added and removed line.

Review Changes

Read added lines in green, removed lines in red, and check the summary of edits.

Diff Tips

Get cleaner, more meaningful comparisons.

Ignore Whitespace

Enable 'Ignore whitespace' when re-indented or reformatted code makes lines look different even though the content is the same.

Ignore Case

Turn on 'Ignore case' to focus on real content changes when only capitalization differs between the two versions.

Swap to Reverse

Use the Swap button to flip original and changed, which is handy for viewing a change as an undo or reversed patch.

Line-Based Comparison

This tool compares whole lines. Keep one sentence or statement per line for the most precise and readable results.