DeskAlerts - Send alerts to any corporate device: PCs, phones, tablets, etc.
OnPage - OnPage critical alert and incident management system enables rapid resolution of critical IT, healthcare or IoT incidents through efficient communication.
One Call Now - One Call Now's message notification delivers automated phone calls, SMS text messages and emails within moments to any group.
Notifuse - A 1-to-many notification API that's simple to use
Metric.live - Real-time and advanced periodic alerts for Google Analytics.
Sweet Alert - Sweet Alert is a replacement for Javascipt's "Alert".