Diff Checker — Compare Text Online
Paste two versions to see what changed. Comparison runs entirely in your browser — nothing is uploaded.
How to compare two texts
- Paste the original text on the left and the new version on the right (or drop two files).
- The differences appear below as you type: removed lines in red, added lines in green, and changed words highlighted inside modified lines.
- Switch between side by side and unified views, and hide unchanged lines with Only changes.
Options
- Ignore whitespace — treats lines that differ only in indentation or spacing as equal (useful for re-indented code).
- Ignore case — treats
Helloandhelloas the same. - Unified view shows changes in the familiar
git diffstyle, with-and+markers.
How it works
The checker uses the Myers diff algorithm — the same approach used by git diff — to find the smallest set of line insertions and deletions
that turns the original into the changed text. Modified lines are then compared word by word to highlight exactly what changed.
Comparing JSON? Format both sides first with the JSON Formatter (with sorted keys) for a cleaner diff.
Frequently asked questions
Is my text uploaded when comparing?
No. The diff is computed in your browser. The texts are only kept in your browser’s local storage so they survive a reload; use Clear to remove them.
Can I compare code?
Yes. The checker works line by line like git diff, so it is well suited to source code, config files, logs and CSV.
How large can the texts be?
Tens of thousands of lines work fine on a typical computer. Very large texts with many differences may take a few seconds.
What does “Ignore whitespace” do?
It collapses runs of spaces and tabs and ignores leading/trailing whitespace when deciding whether two lines are equal.