Authentication

The Square API enables developers to create apps that make API calls on behalf of Square sellers.

Web clients

The OAuth API lets you ask a seller to authorize your app for specific permissions on their Square account and get a scoped access token. The token is used to make authorized API calls on their account resources.

Mobile clients

For developers building mobile applications that take in-person payments using Reader SDK, the Mobile Authorization API lets your mobile app get an authorization code to manage the checkout flow and payment processing on behalf of a seller.