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: 2.15.5

Requirements: macOS >= 10.11

Versions:

Intel tahoe 2.15.5
sequoia 2.15.5
sonoma 2.15.5
ventura 2.15.5
monterey 2.15.5
big sur 2.15.5
catalina 2.15.5
mojave 2.15.5
high sierra 2.15.5
sierra 2.15.5
el capitan 2.15.5

Analytics:

Installs (30 days)
nperf 24
Installs (90 days)
nperf 73
Installs (365 days)
nperf 352