# API Reference source: https://developer.mastercard.com/payment-acceptance-api/documentation/api-reference/index.md ## Environment Domains {#environment-domains} * Sandbox * Production ```Sandbox https://sandbox.api.mastercard.com/commercial/payments ``` ```Production https://api.mastercard.com/commercial/payments ``` ## API Specifications {#api-specifications} API Specification: `https://static.developer.mastercard.com/content/payment-acceptance-api/swagger/payment_acceptance_api.yaml` API Specification: `https://static.developer.mastercard.com/content/payment-acceptance-api/swagger/payment_acceptance_outbound_api.yaml` ## Next Steps {#next-steps} Now that you have a good understanding of all the services endpoints, proceed to the [Testing](https://developer.mastercard.com/payment-acceptance-api/documentation/testing/index.md) section to learn about testing the service.