How can I integrate a payment gateway in flutter framework. Is there any libraries I can use readily? Do I need to do it separately in iOS and Android? In that case which is the best library available in India? Check out the new package for making payment https://pub.dev/packages/flutter_paystack
There are no payment plugins for flutter yet.
To integrate payments into a flutter app, just integrate payments natively and invoke it by implementing a platform channel.
An example of platform channel implementation is shown here.
Hope that helped!