Diff Checker

Paste original and changed text. See added, removed, and edited lines instantly — then copy a unified diff.

A diff checker is a text comparison tool: two pastes, then the shortest list of insertions and deletions that turns the original into the revision. This page runs that pass in the tab — no account, no upload.

Compare two texts

Put the older version on the left and the newer version on the right. The board below marks added lines in green and removed lines in red. Side-by-side view keeps both columns aligned; unified view stacks them like a Git patch.

For a single phrase inside a line, switch Compare to Words or Characters. Ignore case or whitespace when you only care about the wording.

Copy a unified diff

Copy and Download emit a .diff with --- / +++ headers and @@ hunks. Paste that into a review, a ticket, or a patch file.

For search-and-replace instead of a comparison, use Find and replace. To test a regular expression against one paste, use the Regex tester.

Last reviewed 2026-09-10.

FAQ

Questions, answered

Is this a text comparison tool?

Yes. Original on the left, revised on the right, with a highlighted diff below. It is a browser-only diff checker and text compare tool.

Can I compare code or JSON?

Yes. Any plain text works — code, JSON, logs, or prose. Format JSON first with the JSON formatter if you want a tidy comparison.

What is a unified diff?

Copy and download emit the same +/− patch format Git uses, so you can paste it into a review or save a .diff file.

Does my text leave the browser?

No. The diff checker runs in JavaScript on this page. Your paste is not uploaded.

Compare two texts

Copy a unified diff

Questions, answered

Keep going