mqttfx

Install command: 
brew install --cask mqttfx

Name: MQTT.fx

IoT route testing tool

https://www.softblade.de/

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

Cask code: mqttfx.rb on GitHub

Current version: 5.9.0

Requirements: macOS >= 10.15

Versions:

Intel tahoe 5.9.0
sequoia 5.9.0
sonoma 5.9.0
ventura 5.9.0
monterey 5.9.0
big sur 5.9.0
catalina 5.9.0

Analytics:

Installs (30 days)
mqttfx 6
Installs (90 days)
mqttfx 21
Installs (365 days)
mqttfx 119