Tiny Online Tools
Two diffs, because one is never enough
A pixel diff tells you where something moved. A text diff tells you what the words became. This tool does both on every page pair and shows them together.
- Pixels. Both pages are rendered at the resolution you choose and compared channel by channel. Changed areas are painted red, and contiguous bands of changed rows are counted as regions, so "one paragraph edited" reads differently from "the whole page reflowed".
- Text. Each page's text is reconstructed into visual lines and compared line by line, so you get the sentence that changed, not just its coordinates.
Pages are matched, not counted
Comparing page 1 to page 1 is fine until someone inserts a page. After that, every page reads as completely rewritten and the report is useless.
So the two page sequences are aligned by text similarity first, using a bag-of-words overlap and a Needleman–Wunsch alignment with a gap penalty. A page that appears in one document and not the other is reported as added or removed, and the pages around it stay matched. Two pages with no text at all — a scan — score neutrally and stay aligned by position, because there is no evidence either way.
Four ways to look at a change
- Side by side, with a synchronised scroll that is on by default.
- Overlay — the revision with the red change mask painted over it.
- Onion skin — an opacity slider between the two.
- Swipe — a draggable split down the page.
Only the page pair you are looking at is rendered, which is why changing the resolution or the sensitivity is instant even on a long document.
Sensitivity, honestly
Two renderings of the same text do not produce identical pixels: antialiasing and font hinting move edge pixels by a few levels. A sensitivity of 0 therefore reports a document as entirely changed, which is technically true and completely useless. The default of 24 ignores that noise and still catches a changed digit. The slider is there because the right value depends on your document, and the legend always shows the setting a result was produced with.
Export
A JSON or CSV report gives you per page: the status, the change ratio, the number of changed regions and the added/removed line counts. You can also download the composited diff image for the page on screen, or a ZIP of every changed page plus the CSV report.
Privacy
Both files are opened, rendered and compared entirely inside your browser. Nothing is uploaded.