WebGazer is an uptime monitoring platform that checks if your website is up as it should be and notifies you if anything goes wrong
UptimeRobot - Free Website Uptime Monitoring
Website Speed Ranker - Compare how fast your website loads vs your competitors
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Textalyzer - Analyze text readability and SEO parameters
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.
SanityCheck - Get the exact data you need from Google Search Console.