DownNotifier.com is described as 'Free quality website monitoring' and is an website in the Network & Admin category. There are more than 50 alternatives to DownNotifier.com, not only websites but also apps for a variety of platforms, including SaaS, Windows, iPhone and Android. The best alternative is Pingdom. It's not free, so if you're looking for a free alternative, you could try PingPlotter or Down For Everyone Or Just Me?. Other great sites and apps similar to DownNotifier.com are Freshping (Free), StatusCake (Freemium), Ping Tracer (Free, Open Source) and Is It Down Right Now? (Free).
Pingdom web site monitoring and other infrastructure for you and instantly let you know when anything goes wrong. Measure uptime, downtime, and the performance of your website as experienced by visitors.
StatusCake.com is a free website monitoring tool which allows users to track up to 10 websites and get alerted when their site is down or is having trouble. Downtime root cause analysis is included in the free plan to help users diagnose and fix issues.
Pingbreak is an original and free monitoring service. Get notified through Twitter if your website is down. Pingbreak checks all of your websites each minute and alert you instantly by Direct Message (DM).