PDF Diff 4‏+

Easily and quickly see textual differences between PDFs. This is especially useful to see differences in two version of a contract (e.g. developer agreements) or other documents converted to PDF.

Just drag a document to the left and to the right and click compare.
Also allows to easily ignore headers and footers.
Differences can be copied to e.g. emails or text editors (drag & drop).

From the reviews:
map6567: "Impressive App, the app works with very large files. It is lightning fast an produces easy to understand outputs."

Wombloid: "Unbelievable! I've used a lot of PDF comparison software over the years, and always been disappointed. But here I am comparing two annual reports (2019 vs. 2020), both well over 100 pages long ... and PDFDiff is doing a truly impressive job of finding the differences/similarities."