This document introduces the features of Push Notification.

You can send push notifications to users through the Kakao platform using Apple Push Notification service (APNs) or Firebase Cloud Messaging (FCM). To use the push notification function, you need a separate application server ("app server") to receive a push notification because this function is provided through a REST API.

The push notification function has the following advantages:

• Your service does not have to manage the push token manually because Kakao stores and manages the push token internally if you register Android or iOS authentication information on the Kakao platform.
• You can send push notifications to the device where multiple tokens are registered at once because it works based on the service unique ID (uuid).
• You can send push notifications both through APNs and FCM based on the unique ID (uuid) of the service.
• You do not have to build your own message queue server or transmit server separately.

To use the push notification function, you need a server to make a REST API call. You must also make a request by using the app's Admin key registered in Kakao Developers from the server, not from the client-server.

Because the push notification function operates based on uuid, a unique ID should be assigned to each user to identify the receiving users beside push tokens. If you have integrated Kakao Login into your service, you can use id (Service user ID assigned for each Kakao Account) . You can also issue a numeric ID as a Long type for each user.

You can obtain push tokens from APNs or FCM, and the Kakao platform manages the push tokens issued from APNs or FCM. When your app server gets a push token from APNs or FCM, you need to call the Registering push token API using the app's Admin key to register the push token on the Kakao platform that manages each user's push token.

If a user logs out of your service app on Android or iOS or disables the push notification function on a device, the app must notify this change of the app server, so that the app server can delete the push token. When Kakao receives a request to delete a specific push token from your app server, Kakao revokes the corresponding push token based on the requested the user's or device's unique ID.

You can send a push notification when a user triggers a specific event in your service app. For example, you can leverage this feature to let users know when a new comment is left on their posts or when a seat becomes available in the reserved restaurant.

Refer to Scope of support to know whether each Kakao SDK supports each feature.