Util Tools What is a diff checker?
A diff checker compares two pieces of text and highlights exactly what changed between them: which lines or characters were added, removed, or kept the same. It is the same idea behind the "diff" you see in version control like Git, made instant for any two blocks of text you paste in, with no setup.
Reading the output
Differences are colour-coded: additions (text present in the new version) are shown one way, deletions (text removed from the old version) another, and unchanged lines stay neutral. You can compare line by line, which is best for prose and code, or character by character, which pinpoints a single typo or changed value within a line.
Comparing code and documents
A diff is invaluable for spotting what changed between two versions of a file, reviewing edits to a contract or article, checking config files, or confirming that a copy-paste matches the original. Because it shows only the differences, you can scan a large block and immediately see the handful of lines that actually moved.
Your text stays private
This diff checker runs entirely in your browser. The two texts you paste are compared locally with a standard longest-common-subsequence style algorithm and are never uploaded to a server, so it is safe to use with code or sensitive documents.
Last updated: July 2026