Show HN: ParePdf, an app for comparing pdfs

Looks like a great app you built! And love the idea of simply using a color overlay to visualize the difference.

You might want to also look at the verification of contracts as a target market. Often the addition of digital signatures or scanned pages will avoid md5 checksums to check for any tampering. Bacause you approach is visual it might be a great way to validate a contract has not been altered.