They said minor changes only
Drop in the version you sent and the one that came back. Visura shows you every change it finds and, when both files were read in full without OCR, how many passages still match once formatting, page numbers and short repeated lines are set aside.
No account, and nothing is uploaded. Both files are read and compared by this page, on this machine. Open the network tab and check: while a comparison runs, no request leaves with a byte of either document in it.
The version you sent
Drop a file, or
The version that came back
Drop a file, or
One agreement, returned by the other side as a fresh export at a different page size — so it wraps differently, paginates differently and moves its running header — with two clauses genuinely edited. Everything that only looks different has to disappear.