OneSignal Flutter

OneSignal is a popular push notification service that allows you to send notifications to users across various platforms, including Flutter apps.
In flutter, there are several push notification services available with OneSignal being the most popular choices due to its ease of use and robust features. Some popular push notification services you can use with Flutter are:
→ OneSignal
→ Firebase Cloud Messaging (FCM)
→ Pusher Beams
→ AWS Amplify Notifications
→ IBM Cloud Push Notifications

OneSignal and FCM are the popular ones. You can check for FCM here.

Push Notification In Flutter in Background as well as in Foreground Using Firebase

Reasons for choosing OneSignal :

Ease of setup, cross-platform support, rich feature set, user engagement tools, and cost-effective pricing make it a preferred choice for many Flutter developers, especially for those looking for a simpler and more comprehensive solution for managing push notifications across multiple platforms.