Folderglass

Folderglass adds a Quick Look preview for folders. Select a folder in Finder and press Space to see its real size, the kinds of files it holds, its largest and newest files and, for code projects, the git branch, last commit and rendered README. It is useful for checking what a folder contains before you open it. It also renders Markdown files with the same renderer. It suits anyone who browses project and download folders in Finder.

It needs macOS 14 or later, on Apple silicon or Intel. The project says releases from 0.1.3 onward are signed with a Developer ID and notarized. The Quick Look extension is read-only and does not use the network. The app checks GitHub for a newer version when you open it, and you can turn that off in its settings.