DocumentationManage Apps

Register API Overview

The Square Register API uses inter-app communication to let your Android or iOS app open the Square Register app to process in-person payments with Square hardware (including the Square contactless and chip reader).

If you're building a custom point-of-sale app, you can integrate with the Register API to let Square Register handle the payment flow while your app handles everything else.

On iOS and Android, both native and web apps can use the Register API.

For a merchant using your app, the Register API payment flow looks like this:

  1. The merchant uses your app to determine the amount of money to charge a customer.
  2. The merchant's device quickly switches from your app to Square Register, where the amount to charge is pre-populated.
  3. The merchant processes the payment with Square Register.
  4. The merchant's device switches back to your app, which receives information about the result of the transaction.

Processing fees for transactions initiated with the Register API are identical to fees for transactions initiated directly from Square Register. See this article for details.

For more information on whether the Register API is the right solution for your needs, see the Register API section of the FAQ.

Learn how to use the Register API on: