Mentioned By - Learn when your site is mentioned by other sites for free
Snarl - Snarl is a notification system for Windows.
Ultimate Push Notifications by Ecomfit - Retarget customers and protect abandoned cart to boost sale
Notifu - Notifu, a free open source pop-up balloon utility
Ethereum Push Notification Service - Protocol for incentivized, blockchain based notifications.
Notify OSD - Canonicals on-screen-display notification agent, implementing the freedesktop.