The best option for your development team to test the Square SDK integration would be to use the Square Sandbox. The Square Sandbox is a free, isolated server environment that allows you to simulate transactions and test your integration without affecting the production environment. It separates transactions from the production environment and uses test values, so it’s safe for testing purposes.
You can create transactions in the Sandbox by calling Square APIs using API Explorer or your own code. You can use the Sandbox to take payments, create an inventory and subscriptions, and simulate sales and transactions using payment information specifically for use with the Sandbox.
Please note that the Sandbox doesn’t accept valid credit cards. You must use test credit card values found in Sandbox Payments. Also, the Sandbox doesn’t support all features, such as certain Square applications and hardware, and it has some limitations.
Remember, the Sandbox environment is free of charge and you can make an unlimited number of free sandbox API calls. There are no payment processing fees for sandbox payments given that cards aren’t actually charged and payments are never actually processed by a live bank.
For more detailed instructions on how to use the Sandbox, you can refer to the Square Sandbox documentation.
This answer was reviewed by @Bryan-Square.