The beauty if the Internet is that is working for you 24/7. But if your website goes down it could cost you money. Websites can do down at anytime so using a website monitoring program that automatically monitors and evaluates your websites 24/7 is a good idea. These software programs can internet based so there is nothing to upload to your server. Besides, if your server goes down, so will the monitoring program.
Are My Sites Up
Free service notifies you if your sites are down
24/7 Web Monitoring
Free service monitors your websites every 15 minutes and notifies you via email or SMS text if they go down
Up Time Monitoring
Free website monitoring service monitors up to 50 sites (http and https). Notifies you via e-mail, SMS and RSS (Twitter coming soon). Monitors every website every 5 minutes.
Host Tracker
Free website uptime monitoring service
