# Paypal Docs ## Docs - [Get started with PayPal REST APIs](https://docs.paypal.ai/developer/how-to/api/get-started.md) - [Handling API responses when integrating with PayPal APIs](https://docs.paypal.ai/developer/how-to/api/handling-api-responses.md) - [Making PayPal REST API requests](https://docs.paypal.ai/developer/how-to/api/make-api-requests.md) - [Rate limiting with PayPal REST APIs](https://docs.paypal.ai/developer/how-to/api/rate-limiting.md) - [Agreement already canceled](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/agreement-already-cancelled.md) - [Cannot pay self](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/cannot-pay-self.md) - [Currency mismatch](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/currency-mismatch.md) - [Currency not allowed](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/currency-not-allowed.md) - [Duplicate transactions](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/duplicate-transaction.md) - [Merchant not enabled for reference transaction](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/merchant-not-enabled-for-reference-transaction.md) - [Not authorized](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/not-authorized.md) - [Common errors overview](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/overview.md) - [Resource not found](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/resource-not-found.md) - [Unprocessable entity](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/unprocessable-entity.md) - [Unsupported payee currency](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/unsupported-payee-currency.md) - [Validation error](https://docs.paypal.ai/developer/how-to/api/troubleshooting/common-errors/validation-error.md) - [Handling payment failures with PayPal](https://docs.paypal.ai/developer/how-to/api/troubleshooting/handling-payment-failures-with-paypal.md) - [Apps, scopes, and credentials](https://docs.paypal.ai/developer/how-to/apps-scopes-credentials.md) - [Advanced configuration](https://docs.paypal.ai/developer/how-to/sdk/js/v6/advanced.md) - [Set up JavaScript SDK v6](https://docs.paypal.ai/developer/how-to/sdk/js/v6/configuration.md) - [Sandboxed