> For the complete documentation index, see [llms.txt](https://docs.digitalriver.com/commerce-api-references/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide.md).

# Commerce API reference guide

- [API structure](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure.md): Understand the Commerce API structure.
- [API keys](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/api-keys.md): Understand how to use your API keys.
- [Supported OAuth and Commerce API formats](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/supported-oauth-and-commerce-api-formats.md): Learn about supported OAuth and Commerce API formats.
- [Mini cart widget](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/mini-cart-widget.md): Understand how to use a Mini Cart widget.
- [Custom attributes](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/custom-attributes.md): Learn about custom attributes.
- [Fields used as keys](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/fields-used-as-keys.md): Learn how to use fields as keys.
- [Fields and expand query parameters](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/fields-and-expand-query-parameters.md): Learn how to use field and expand query parameters.
- [Caching responses](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/caching-responses.md): Learn when to cache responses.
- [CORS support](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/cors-support.md): Understand how CORS defines how a browser and server communicate.
- [JSONP support](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/jsonp-support.md): Understand how JSONP works.
- [Transport](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/transport.md): Understand how transport works.
- [Service profiles](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/service-profiles.md): Understand service profiles.
- [Supported protocols and formats](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/supported-protocols-and-formats.md): Understand data transport protocols and formats.
- [Elements](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/elements.md): Learn how to handle unknown elements.
- [Rate limiting](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/rate-limiting.md): Understand rate limiting.
- [Locale and currency](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/locale-and-currency.md): Understand how to use locale and currency.
- [Exchange rate](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/exchange-rate.md): Understand how Digital River manages the exchange rate.
- [Product identifier](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/product-identifier.md): Understand the product identifier.
- [Product external reference identifier (ERID)](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/product-external-reference-identifier-erid.md): Understand the product ERID.
- [Customer external reference identifier ERID](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/customer-external-reference-identifier-erid.md): Understand the customer ERID.
- [Cancel request process](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/cancel-request-process.md): Learn how to handle various Cancel Request scenarios.
- [Failover and redundancy](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/failover-and-redundancy.md): Understand how Digital River provides failover and redundancy.
- [Troubleshooting API calls](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/api-structure/troubleshooting-api-calls.md): Learn how to resolve problems with API calls.
- [Shopper APIs reference](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference.md)
- [Carts](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/carts.md): Learn more about the carts resource.
- [Offers](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/carts/offers.md): Understand how offers work.
- [Offer types](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/carts/offers/offer-types.md): Understand the available offer types.
- [POP offers](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/carts/offers/pop-offers.md)
- [Applied offers](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/carts/offers/applied-offers.md)
- [Eligible offers](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/carts/offers/eligible-offers.md)
- [Orders](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/orders.md): Learn more about the orders resource.
- [Returns](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/returns.md): Learn how returns are processed.
- [Links](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/shopper-apis-reference/links.md): Understand how the Shoppers resource includes links.
- [Admin APIs reference](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference.md)
- [Subscriptions](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/subscriptions.md): Learn how to manage subscriptions.
- [Sites](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/sites.md): Understand the basics of sites.
- [Products](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/products.md): Understand the basics of products.
- [Live changes](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/live-changes.md)
- [Authorized shipping and billing countries](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/authorized-shipping-and-billing-countries.md): Understand shipping and billing countries.
- [Merchandising](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/merchandising.md): Learn how to use offers, point-of-promotions (POPs), and private stores.
- [Disclosures](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/admin-apis-reference/disclosures.md): Learn how to apply disclosures.
- [Glossary](https://docs.digitalriver.com/commerce-api-references/commerce-api-reference-guide/glossary.md)