Snowball Smart Notifications - Get the notifications you want and none of the rest
OneSignal - Customer engagement platform used by over 1 million developers and marketers; the fastest and most reliable way to send mobile and web push notifications, in-app messages, emails, and SMS.
Pingy - Check your site status from your menubar
Mixpanel - Mixpanel is the most advanced analytics platform in the world for mobile & web.
Hooks Chats - Push notifications meet real time conversations
Pushy - Pushy is a reliable push notification gateway for time-sensitive, mission-critical apps.