In addition to providing REST APIs and webhooks for integrating with external systems, and widgets for extending your storefront, Commerce Cloud also includes support for developing server-side extensions written in JavaScript.

Server-side extensions are built using the Express web framework and executed in the Node.js runtime environment. These extensions implement custom REST endpoints, which have the prefix /ccstorex/custom. For example, you could create a custom shipping calculator whose path is /ccstorex/custom/v1/calculateShipping.

For more information about developing server-side extensions, see the following post on Oracle PartnerNetwork:

https://community.oracle.com/groups/oracle-commerce-cloud-group/
blog/2017/07/21/working-with-commerce-cloud-server-side-extensions