spaceid

Install command: 
brew install --cask spaceid

Name: SpaceId

Menu bar indicator showing the currently selected space

https://github.com/dshnkao/SpaceId/

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

Cask code: spaceid.rb on GitHub

Current version: 1.4

Requirements: macOS >= 10.12

Analytics:

Installs (30 days)
spaceid 64
Installs (90 days)
spaceid 216
Installs (365 days)
spaceid 937