Question 1

What algorithm does this diff checker use?

Accepted Answer

This tool uses a Longest Common Subsequence (LCS) algorithm to compare lines. LCS finds the longest sequence of lines that appear in both texts in the same order, then marks everything else as an addition or removal. This is the same fundamental approach used by git diff and the classic Unix diff utility.

Question 2

Is my text sent to a server?

Accepted Answer

No. This diff checker runs entirely in your browser using JavaScript. Your text never leaves your device - there are no API calls, no server processing, and no data storage. You can verify this by checking the Network tab in your browser's developer tools.

Question 3

What does the ignore whitespace option do?

Accepted Answer

When 'Ignore whitespace' is enabled, the diff algorithm treats lines that differ only in leading, trailing, or internal spacing as identical. This is useful when comparing code that has been reformatted or re-indented, so you can focus on meaningful content changes rather than formatting differences.

Question 4

Can I compare large files with this tool?

Accepted Answer

Yes. Since the tool runs locally in your browser, there are no upload size limits. However, extremely large files (tens of thousands of lines) may take a moment to process depending on your device's performance. For best results with very large files, close other browser tabs to free up memory.