Text Diff Checker

Word-by-word (token-level, actually — words and punctuation are compared separately). That matters for prose edits: a line diff would treat an entire rewritten paragraph as one giant change, even if you only swapped a couple of words. A word-level diff pinpoints exactly which words changed inside a sentence, which is far more useful when you're reviewing an edited page's copy.

Yes. The comparison algorithm builds a table whose memory use grows with the product of both texts' lengths, so extremely large pastes could freeze the tab. Each box is capped at a few thousand tokens (words, spaces, and punctuation combined) — comfortably enough for a full blog post or page of copy, but not an entire book.

No. The comparison runs entirely in your browser — nothing you paste into either box is uploaded to a server.

Comparing a before/after when editing a page's copy, checking exactly what changed between two drafts before you publish, or verifying that a content update didn't accidentally delete something important — like a keyword-rich sentence or a disclosure line — while trimming a paragraph.

Not directly — this tool compares whatever text you paste into the two boxes. To compare two live URLs, use the site's Duplicate Content Checker tool instead, which takes two URLs and measures text overlap between them directly rather than showing a token-level diff.