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

WebGazer - Monitor your website's availability with WebGazer, review its performance and get instant notifications when your website goes down. No installation required and free plan available.

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

Oh Dear! - Website monitoring, without the hassle

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.

updown.io - updown.io is a HTTP(S)/TCP/ICMP monitoring service which checks periodically the URL you want and reports back any anomaly.