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Developer Utilities · Free tool

Diff Checker

Paste two blocks of text and see what changed line-by-line. Great for contracts, code, and writing revisions.

Updated April 2026

What it does

Paste two blocks of text — a previous and current version of a contract, a commit message, or a draft — and see exactly which lines changed. Unchanged lines appear grey on both sides; removed lines are red on the left, added lines are green on the right. The diff is a standard LCS-based line comparison, same idea as diff on a Unix shell.

For comparing structured text like JSON, reformat both sides first with JSON Formatter before running the diff — identical data can otherwise show as completely different if whitespace or key order shifted.

How to use it

  1. Paste the original text on the left.
  2. Paste the changed text on the right.
  3. Click Compare — scroll through the side-by-side result.
  4. Red = removed, green = added, grey = unchanged.