WebGazer is an uptime monitoring platform that checks if your website is up as it should be and notifies you if anything goes wrong
Hyperping - Cheap uptime and performance monitoring with detailed reporting and flexible alerting
UptimeRobot - Free Website Uptime Monitoring
Downtime Bot for Telegram - Get alerts when your site gives errors via a Telegram Bot 🤖
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
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.
Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.