Diff Checker
Paste the original on the left and the changed version on the right. Differences are highlighted line by line and word by word as you type.
How to read the diff
Lines only in the original are marked − and tinted red; lines only in the changed text are marked + and tinted green. When a line was edited rather than replaced, the exact words that changed are highlighted inside it, so a one-character fix in a long paragraph is easy to spot.
Side by side lines the two versions up in columns; Unified shows one column, the way Git and code review tools do. Turn on Only changes to hide long unchanged stretches, keeping three lines of context around each change. Click a “Show unchanged lines” bar to expand it.
The comparison uses the Myers algorithm, the same approach behind git diff, so it finds the smallest set of added and removed lines.
Questions
Are my texts uploaded to compare them?
No. The diff runs entirely in your browser. Your two texts are kept in this browser’s local storage so they survive a refresh, and nowhere else.
What does “Ignore whitespace” do?
It treats runs of spaces and tabs as a single space and ignores leading and trailing spaces, so re-indented code or double spaces after a full stop do not show up as changes.
Can I compare two files?
Yes. Use “Open file” above each box to load any plain-text file — code, CSV, Markdown, logs — up to 5 MB. The file is read locally and never leaves your device.
What is “Copy patch”?
It copies the differences in unified diff format (the @@ -1,4 +1,4 @@ style used by Git), which you can paste into a code review, an email or apply with git apply or patch.
Why is a changed line shown as fully removed and re-added?
If less than about a third of the words in a line survive, highlighting individual words becomes noise, so the whole old line and new line are shown instead.