Question 1

How does the text comparison work?

Accepted Answer

The diff checker uses the Longest Common Subsequence (LCS) algorithm to find the maximum shared content between the two texts, then marks everything not in the LCS as either added or removed. This is the same algorithm used by Git and Unix diff utilities.

Question 2

What do the colors mean in the diff output?

Accepted Answer

Green lines with a + prefix are lines that exist in the modified text but not in the original (additions). Red lines with a − prefix exist in the original but not in the modified text (deletions). Unmarked lines appear in both texts unchanged.

Question 3

Can I compare source code with this tool?

Accepted Answer

Yes. The diff checker works on any plain text including source code, configuration files, JSON, HTML, CSS, and JavaScript. For code, make sure both versions are plain text — do not paste formatted code from a rich text editor.

Question 4

Is there a limit on text size?

Accepted Answer

The diff runs entirely in your browser using JavaScript. Very large texts (100,000+ characters) may take a few seconds due to the O(m×n) LCS algorithm complexity. For extremely large files, consider a dedicated diff tool like VS Code's built-in diff editor.

Question 5

Can I use this to compare Word documents?

Accepted Answer

Paste the plain text content of your Word documents (use Ctrl+A, Ctrl+C in Word and paste here). The diff checker compares text only, not formatting, images, or metadata. For full document comparison with formatting, use Word's built-in "Compare Documents" feature.

Question 6

Does the comparison preserve whitespace?

Accepted Answer

Yes. The diff compares lines exactly including leading and trailing whitespace. A line with extra indentation will be marked as changed. If you want to ignore whitespace differences, manually normalize your text before comparing.

Question 7

How do I find which version has more content?

Accepted Answer

Check the summary row at the top of the results: it shows "X added lines" (green), "Y removed lines" (red), and the count of unchanged lines. More added lines means the modified version has more unique content; more removed lines means the original had content that was deleted.

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