Build a secure payment client for Android devices with the In-App Payments SDK.
In-App Payments SDK

Build on Android

To build with the In-App Payments SDK on Android, the following must be true:

  • Your application minSdkVersion is API 24 (Nougat, 7.0) or later.

  • You have added the In-App-Payments SDK to your Android project. For more information, see Install In-App-Payments SDK.

  • You have a Square account enabled for payment processing. If you have not enabled payment processing on your account (or you are not sure), visit

Additionally, this guide makes the following assumptions:

  • You keep the payment form open when processing payments. The In-App Payments SDK provides two ways to access the payment token depending on whether you want to keep the payment form open while processing payments. The payment processing steps in this guide assume that the form stays open. To process payments in the background, see Connect to a Backend Service for the relevant changes.

  • You are generally familiar with developing applications on Android. If you are new to Android development, you should read the Getting Started Guide on the Android Developers site before continuing.


    While the In-App Payments SDK supports payments for physical and digital sales, using the In-App Payments SDK to process digital sales might not be allowed by some mobile application distribution services (such as App Store and Google Play) and might result in your application being removed. Examples of digital sales include intangible goods (such as in-game assets), online services (such as upgrades in application functionality), and digital subscriptions (such as cloud or streaming services).

    To avoid the potential removal from application distribution platforms, the In-App Payments SDK should only be used to process sales of goods or services that are consumed outside the application. You should review the terms of service for the respective mobile application distribution services you use to ensure that you are compliant with their guidelines.

Complete the following items to start the card entry flow.

  1. Set a click listener on a button.

  2. In the button click listener, call startCardEntryActivity on CardEntry and pass a reference to the activity that starts the card entry flow.


    When testing your application in the Square Sandbox, be sure to use Sandbox test values to enter card information.

In the onActivityResult method, call the static CardEntry.handleActivityResult method with the activity results object (CardEntryActivityResult) and an anonymous method that contains your logic for responding to the card entry completion.

In the anonymous method, get a CardDetails object from the activity result and then call the getNonce() function to get the payment token.

Declare a class that implements CardNonceBackgroundHandler to call your backend service and process the payment token while the payment form is still open.

The previous example refers to myBackendService, which is a placeholder for the backend service that you must create so that your application can process the payment token received from the In-App Payments SDK. The backend service calls the Payments API to create a payment that charges the card entered by a buyer in your mobile client. For more information about taking a payment, see Take a payment using a secure token.

When your backend service has received the payment token from your mobile application, it can take a payment but it can also use the token to store a card on file for the customer. Your mobile application must provide enough customer information for the backend to find the customer using the SearchCustomers endpoint. For example, if your mobile application has the buyer's email address and sends it to your backend along with the payment token.

To learn about how to save a card on file from your backend, see Create a Card on File and a Payment.

In your application class, set CardEntry.cardNonceBackgroundHandler to reference CardEntryBackgroundHandler.


The CardEntryBackgroundHandler must be set in the application class so that it is set again if the application process is stopped and later restarted on the card entry flow.

If you need more assistance, contact Developer Support or ask for help in the Developer Forums.