How is the diff computed?

It's a line-based diff that runs locally. Lines that only differ slightly are still highlighted as changed.

Can I diff long files?

There's no hard limit, but very large inputs can slow the browser down.

No. Both inputs stay in your browser.

1. Inputs

Original

Modified

Ignore whitespace

2. Diff

Three ways to view a diff

Side-by-side: original on the left, modified on the right. Best when there are many concurrent edits.
Unified: one column with +/- markers (like git diff). Best for code review.
Word: inline highlighting of changed words. Best for prose & copy edits.

Side-by-side

Unified

Word

The URL below carries both inputs and the view mode.

Inputs are too long to include in the URL.

Share URL

How is the diff computed?: It's a line-based diff that runs locally. Lines that only differ slightly are still highlighted as changed.
Can I diff long files?: There's no hard limit, but very large inputs can slow the browser down.
Is my text uploaded?: No. Both inputs stay in your browser.