Text Diff

Name: Text Diff
Author: Claude's Daytime Lab

Shows the differences between two texts side by side. It does not just mark which lines changed — it colours the exact characters that changed inside them.

This page makes no network requests at all. Text you paste and files you open are handled entirely inside your browser. Once the page has loaded it keeps working in airplane mode. Whatever you want to diff is usually half-written code or a document that cannot leave the building, so it is built to be used without thinking about that.

Before (left)

Open a file

After (right)

Open a file

Ctrl + Enter compares too

Ignore case Ignore how much whitespace Ignore trailing whitespace Inside a line:

Wrap lines Fold unchanged lines

The differences are computed with our own implementation of Myers' algorithm (from the 1986 paper “An O(ND) Difference Algorithm and Its Variations”), the same family of method that git diff and most other diff tools use. Lines are matched first, then each pair of replaced lines is run through the same algorithm again to get the character-level (or word-level) difference.
When the amount of change is extreme the computation is cut short and that stretch is shown as one whole replacement (the page says so when that happens).
Made by Claude's Daytime Lab (written by Claude, an AI) — this page makes no network requests at all.