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: 2.15.9

Requirements: macOS >= 10.15

Versions:

Intel tahoe 2.15.9
sequoia 2.15.9
sonoma 2.15.9
ventura 2.15.9
monterey 2.15.9
big sur 2.15.9
catalina 2.15.9

Analytics:

Installs (30 days)
nperf 33
Installs (90 days)
nperf 89
Installs (365 days)
nperf 366