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: 2.15.10

Requirements: macOS >= 10.15

Versions:

Intel tahoe 2.15.10
sequoia 2.15.10
sonoma 2.15.10
ventura 2.15.10
monterey 2.15.10
big sur 2.15.10
catalina 2.15.10

Analytics:

Installs (30 days)
nperf 25
Installs (90 days)
nperf 95
Installs (365 days)
nperf 356