KnownOutage - Quickly and easily alert people when there is an issue or outage with your service.
Cachet - Cachet is a free, open source status page for your API, service or company. Built with all of the features that you'd expect from a status page.
cState - 🔥 Free & open source under MIT!
tawk.to - tawk.to is a free live chat app that lets you monitor and chat with visitors on your website or from a free customizable page
Status.io - Status.io is a platform for system status pages and status notifications. Companies rely on Status.io to track outages, schedule planned maintenances, broadcast status notifications, and much more; and their customers love the transparency.
Smashing - Smashing is a fork of Dashing (which is no longer maintained), a Sinatra based framework that lets you build beautiful dashboards.