Here i have compiled 5 web sites giving free web monitoring services. The first one is best as i am using it myself.

1. HyperSpin

Website monitoring, web server monitoring & server monitoring from worldwide locations. Receive downtime alerts via SMS & Email.

2. Mon.itor.us

Mon.itor.us is a free, yet powerful website, server and traffic monitoring service. It is a part of Monitis family, which provides professional, premium all-in-one monitoring service, integrating application performance with backend infrastructure with cloud monitoring.

3. Site 24×7

Site24×7 is the easier, faster and effective way to monitor the uptime & performance of your websites, online services & servers.

4. Internet Vista

InternetVista® is a monitoring infrastructure that watches over your website 24 hours a day and 7 days a week. If it is unavailable or malfunctioning, you are immediately notified by email and by SMS.

5. Server Mojo

There are those whose servers have downtime, and those who don’t know their servers have downtime. Either way, ServerMojo is exactly what you need.