How does the diff algorithm work?

It uses a Longest Common Subsequence (LCS) algorithm to find matching lines and highlights additions and removals.

Can I compare large texts?

Yes. The comparison runs entirely in your browser and can handle large documents, though very large texts may take a moment to process.

Green backgrounds indicate lines that were added in the modified text. Red backgrounds indicate lines that were removed from the original.

No. All diffing is done locally in your browser. Your text never leaves your device.

Compare two texts and see the differences highlighted line by line.

Original

Modified

Step 1

Paste the original text into the left textarea.

Step 2

Paste the modified text into the right textarea.

Step 3

Click Compare to run the diff.

Step 4

Review the highlighted output below to see additions and removals.

Line-by-line diff using the LCS algorithm.

Added lines highlighted in green, removed lines in red.

Handles large documents entirely in the browser.

No data sent to any server -- fully client-side.

Free to use with no sign-up required.

: It uses a Longest Common Subsequence (LCS) algorithm to find matching lines and highlights additions and removals.
: Yes. The comparison runs entirely in your browser and can handle large documents, though very large texts may take a moment to process.
: Green backgrounds indicate lines that were added in the modified text. Red backgrounds indicate lines that were removed from the original.
: No. All diffing is done locally in your browser. Your text never leaves your device.