Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.

Netumo - Ensure healthy website performance, uptime, and free from vulnerabilities. Automatic checks for SSL Certificates, domains and monitor issues with your websites all from one console and get instant notifications on any issues.

NetGuard - NetGuard

AppZero - AppZero is a monitoring and migration tool that allows users to keep track of different applications and servers in both simple and complex IT environments.

Portmaster - Is a Privacy Modular Privacy App which includes a "DNS over TLS" feature as well as an "Application Firewall".

RedGate SQL Monitor - SQL Monitor helps you and your team find issues – before they become problems