Square

1. Get started

   Account, application and first request.

2. Authentication

   Access tokens and authentication.

3. OAuth

   OAuth to act on behalf of sellers.

4. Payments API

   Taking payments with the Payments API.

5. Web Payments SDK

   Tokenizing cards in the browser with the Web Payments SDK.

6. Orders

   Creating and managing orders.

7. Catalog

   Items, variations and categories.

8. Customers

   Customer profiles and groups.

9. Subscriptions

   Recurring billing with subscriptions.

10. Webhooks

    Webhook subscriptions and signature verification.

11. Idempotency and patterns

    Idempotency keys and cursor pagination.

12. Errors

    Handling API errors.

13. Sandbox

    Sandbox testing.

14. Versioning

    API versions and upgrades.

15. Terminal API

    Taking card-present payments with Terminal.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.