Metronomus - Powerful and beautiful online metronome
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.
afractal Metronome - Highly perfomant, easy to use, minimalistic digital metronome desktop app.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
AudioKit Hey Metronome - Visit the post for more.
Better Uptime - We call you when your website goes down