Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting

ServerSuit - ServerSuit is a browser based program that enables remote Linux administration, monitoring, website hosting, and server setup automation.

Downtime Bot for Telegram - Get alerts when your site gives errors via a Telegram Bot 🤖

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

TaskCall - TaskCall is an incident response and management service that helps organizations digitize their operations and reduce downtime costs to the minimum by mobilizing their response effort and streamlining stakeholder communication.

Nagios - Complete monitoring and alerting for servers, switches, applications, and services