Push notifications are specific to your web development framework. Because it is the server maintaining an open port for
pushing the notification to client. On simple web interface, ASP.NET SignalR is enough and you can use JavaScript to handle new messages.
What you need is already solved (in a general way) on this following link, you just need to trigger the message on
change event.
Tutorial: Getting Started with SignalR 2 and MVC 5 | The ASP.NET Site[
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However if you mean native mobile notifications, then are also device specific, such as Google Firebase for Android etc. You would require separate keys for iOS, Windows Phone and Kindle etc. They all have their own implementations and access methods for notifications. You might be interested in them if you know how-to,
Firebase | App success made simple[
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Microsoft Azure allows you to use a hub to enable push notifications cross-device. using their keys through one portal.
Notification Hubs - Mobile push notifications | Microsoft Azure[
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