contexts

Install command: 
brew install --cask contexts

Name: Contexts

Allows switching between application windows

https://contexts.co/

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

Cask code: contexts.rb on GitHub

Current version: 3.9.0

Requirements: macOS >= 10.11

Versions:

Intel mojave 3.7.1
high sierra 3.7.1
sierra 3.7.1
el capitan 3.7.1

Analytics:

Installs (30 days)
contexts 65
Installs (90 days)
contexts 208
Installs (365 days)
contexts 900