Diffchecker 5.1.3 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. The program lies within Productivity Tools, more precisely Office Tools. The actual developer of this free software for Mac is Checker Software Inc.
From the developer:
Diffchecker is an application that compares differences on the spot. The tool lets you compare text from documents, Text files, and PDFs. Also, it can compare images in photos, graphics, and scans. Diffchecker provides features such as unified differences view, character-level differences, and folder differences. It can export to PDF and supports syntax highlighting.