About Diffline

Diffline is a free tool that shows you the difference between two texts, quickly and privately.

Why it exists

Comparing two versions of something is a small job that comes up all the time: a contract that came back with edits, a config file that stopped working, a draft your editor tidied up. Most online tools for this are slow, cluttered, or quietly upload whatever you paste. Diffline was built to be the opposite: open the page, paste, see the changes.

How it works

Diffline uses the Myers diff algorithm, the same method behind Git, to find the smallest set of changes between two texts. Lines that were edited get a second pass that highlights the exact words that changed. You can view the result side by side or inline, ignore differences in case or spacing, and hide unchanged lines.

Private by design

Everything happens inside your browser. Your text is never uploaded, stored or logged. There is no account and nothing to install. See the Privacy Policy for the full details.

Keeping it free

Diffline is free to use and will stay that way. To cover its costs, it may show a small number of ads from Google AdSense. Ads never see the text you compare.

Get in touch

Found a bug or have an idea? Visit the Contact page. Feedback from people who use the tool is the main thing that shapes what gets built next.