The program is simply using OS X’s built-in PDF-processing features to strip PDF files of all the unnecessary bits: preview images, metadata, and the like. This feature is especially useful for PDFs created in Adobe Illustrator and InDesign, which tend to be unnecessarily large because of program-specific components and other non-vital data these applications save inside each PDF.

Meerkat turns SSH tunnels — a fairly obscure and complicated concept — into a feature anyone should be able to use, and does so in a very Mac-like way.