Diff Checker · Compare Text

How to compare two texts (free)

1. Paste the original text on the left and the changed text on the right.
2. Pick a mode: lines for code and configs, words for prose, characters for short strings.
3. Changes highlight instantly — green was added, red was removed.

Line, word or character diff?

Compare lines treats each line as a unit — the classic source-code diff, and the right choice for configs, CSV rows and logs. Compare words looks inside lines and highlights just the words that changed — much easier to read for contracts, essays and documentation. Compare characters shows single-character edits, which is what you want for URLs, keys and IDs that differ by one letter.

Getting a patch file

Copy patch puts a standard unified diff on your clipboard — the same --- / +++ / @@ format produced by git diff. Save it as changes.patch and apply it with git apply or the patch command.

Why katlab's diff checker is different

Popular diff sites run the comparison on their servers, which means both versions of your text are uploaded. This one compares entirely inside your browser tab — safe for contracts, unreleased copy, source code and anything under NDA. It also works offline once the page has loaded.

Is there a size limit?

No hard limit — the comparison runs on your machine. Very large texts (hundreds of thousands of lines) simply take longer, since diffing is O(n·d) in the size of the change.