Clerk - Clerk.io, the artificial intelligence for e-commerce that knows your customers interests.

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

Twilio for Slack - Enable SMS conversations with Slack+Twilio

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.

Spike.sh - Spike is an incident management platform that alerts via slack, phone and email and automatic escalations to help teams fix infrastructure problems.

Checkify - Super minimal, simple and inexpensive 24/7 uptime monitoring