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.
Google Analytics - Improve your website to increase conversions, improve the user experience, and make more money using Google Analytics. Measure, understand and quantify engagement on your site with customized and in-depth reports.
UptimeRobot - Free Website Uptime Monitoring
StatCounter - StatCounter is a simple but powerful real-time web analytics service that helps you track, analyse and understand your visitors so you can make good decisions to become more successful online.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
Matomo - Matomo is an open-source web analytics platform