Reliable website uptime monitoring https://www.freshworks.com/website-monitoring/

CULA controls your site’s performance, response time and availability, notifies you about any downtime and allows you to check for content on any sites you choose. What’s more, CULA can monitor your servers and collect essential data. https://cula.io/

Website Uptime & Performance Monitoring

Powerful monitoring tools that are quick-and-easy to set up. Instant alerts that you can trust, the moment your site goes down. Gain invaluable insights into how your website’s performance is impacting your customers’ experiences – helping your business to stay ahead of the competition. https://www.statuscake.com/

ServerBeep.com is a free server and website monitoring service. We check your website or your service every 10 minutes. You can register an account, add your website or services like FTP or POP3 and if something goes wrong you will get an email notification. Simple, ready to use, reliable. https://www.serverbeep.com/

http://www.uptimedoctor.com/