What are some alternatives?
When comparing Pingoscope and NIXStats, you can also consider the following products
UptimeRobot - Free Website Uptime Monitoring
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.
StatusCake - StatusCake | Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
upTom - Free simple website monitoring tool.
Site24x7 - Site24x7 offers both free & paid website monitoring services. Monitor websites remotely and receive instant email/sms alerts if your website becomes unavailable. View uptime & performance graphs of your website monitors.
PHP Server Monitor - PHP Server Monitor is a script that checks whether your websites and servers are up and running.