Pusher Beams - Send push notifications programmatically at scale
Mentioned By - Learn when your site is mentioned by other sites for free
Push Notification Preview - A simple tool for previewing push notification copy
Ultimate Push Notifications by Ecomfit - Retarget customers and protect abandoned cart to boost sale
Ethereum Push Notification Service - Protocol for incentivized, blockchain based notifications.
Snowball Smart Notifications - Get the notifications you want and none of the rest