OnlineOrNot - Uptime monitoring for software teams (even teams of one).

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.

Statsignal - Statsignal is a simple and cost-effective way to monitor your website or server and publish a status page of your system.

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.

Uptime Kuma - A fancy self-hosted monitoring tool.

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