Text Diff Checker

Text is compared line by line using a longest-common-subsequence algorithm, the same technique used by most "diff" tools — it finds the smallest set of added and removed lines needed to turn the original into the changed version.

When a line was edited rather than added or deleted outright, it is matched with its counterpart and compared character by character. The lighter tint marks the whole changed line, while the deeper green or red marks the exact characters that were inserted or removed.

Yes. Use the Upload button above either box to load a text-based file — .txt, .md, .csv, .json, .xml, .yaml, or any common source-code file. The file is read locally in your browser and never uploaded.

Each block of changes becomes a hunk you can resolve individually — keep the original side, the changed side, or both. Unchanged lines are carried through untouched, and the combined result can be copied or downloaded as a .txt file.

The PDF is a paginated report of the full comparison with added lines shaded green and removed lines shaded red. The Excel export is a spreadsheet with original and changed line numbers, both versions of each line, and a change type column, so you can filter and review the differences.

No. Comparing, merging, and generating the PDF and Excel files all run entirely in your browser — nothing is sent to a server.