What a diff checker does
A diff checker compares two versions of the same text and shows what is different. Lines that only exist in the original are marked as removed. Lines that only exist in the new version are marked as added. Everything else is left alone.
People use one to review an edit, to check what a colleague changed in a contract, to compare two config files or to confirm that a copy and paste did not lose anything.
How to compare two texts
Paste the original text in the left box and the changed text in the right box. You can also drop a file onto either box. Then press Compare, or use Ctrl+Enter.
- Choose side by side or a single combined view.
- Ignore whitespace or letter case when those changes are noise.
- Collapse unchanged lines to focus on the changes.
- Copy the result as a unified patch, or download it as a .diff file.
Line changes and word changes
The checker finds the longest run of lines the two versions share, and treats the rest as changes. Inside a changed line it can also highlight the words that moved, so a one-word edit in a long paragraph is easy to spot.
Big inputs are compared in the background, so the page stays responsive even with thousands of lines.
Your text stays private
The comparison runs on your computer. Nothing you paste or load is uploaded, stored or logged, which makes it safe for drafts, contracts and source code.
Frequently asked questions
Is my text uploaded when I compare it?
No. The whole comparison runs in your browser. The text never leaves your computer.
How do I compare two files?
Drop each file onto its box, or use the open button on each side. The checker reads the files locally and compares them when you press Compare.
Can I ignore spaces or capital letters?
Yes. Turn on the ignore whitespace option, or the ignore case option, and lines that differ only in those ways are treated as equal.
What is a unified diff?
It is the standard patch format used by Git and most developer tools. You can copy it or download it from this page and apply it elsewhere.