API REST FLUTTER MOBILE EXPERT

i am developing a mobile app using flutter that need integration with payment gateway to add credit cards using tokenization method and process online transactions.

Payment gateway offer API REST METHOD for integration into mobile apps

GUIDE
https://developer.cybersource.com/library/documentation/dev_guides/Secure_Acceptance_Checkout_API/Secure_Acceptance_Checkout_API.pdf

ABOUT THE APP:

The app its developed using flutter, my developer its managing others features so i need someone who work the payment gateway job together with him.

i understand its required to develop the backend logic and then create the flutter module to interact with backend.

IMPORTANT NOTES–>

1. The payment details should be entered directly on the app and not on browser inside the app.

2. Payment gateway do not offer SDK for mobile. The job need to be done using API REST