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.
PushCrew - Push Notifications for Websites
Webpushr - World most trusted web push notification platform. All browsers (Safari, Chrome, IE, Firefox, etc.
PushEngage - Personalized Browser Push Notifications.
iZooto - Engage your mobile and desktop web users with intelligent web push notifications.
PushOwl - Re-engage website visitors with push notifications