skim

Install command: 
brew install --cask skim

Name: Skim

PDF reader and note-taking application

https://skim-app.sourceforge.io/

Cask JSON API: /api/cask/skim.json

Cask code: skim.rb on GitHub

Current version: 1.7.11

Requirements: macOS >= 10.13

Analytics:

Installs (30 days)
skim 841
Installs (90 days)
skim 2,635
Installs (365 days)
skim 11,542