nperf

Install command: 
brew install --cask nperf

Name: nPerf

Internet speed test utility

https://www.nperf.com/

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

Cask code: nperf.rb on GitHub

Current version: 1.12.3

Current version requires: macOS >= 10.11

Versions:

Intel tahoe 1.12.3
sequoia 1.12.3
sonoma 1.12.3
ventura 1.12.3
monterey 1.12.3
big sur 1.12.3
catalina 1.12.3
mojave 1.12.3
high sierra 1.12.3
sierra 1.12.3
el capitan 1.12.3

Analytics:

Installs (30 days)
nperf 18
Installs (90 days)
nperf 76
Installs (365 days)
nperf 347