When retrieving data via callouts from a REST API, which adapter should be used?

When retrieving data through callouts from a REST API, using a Custom Adapter for Salesforce Connect is the most suitable choice because it provides the necessary flexibility to interact with REST APIs that do not conform to a standard protocol.

Custom Adapters allow developers to define how Salesforce interacts with external applications or services by specifying the endpoints, authentication methods, and data formats required for communication. This flexibility is essential when working with a REST-based API, as it may not fit the constraints of standard Salesforce adapters that are designed for specific service types like OData or other predefined services.

In contrast, other adapters, such as the OData 2.0 Adapter, are typically geared toward accessing OData services specifically and may not support the diversity of REST API structures. Similarly, the Salesforce Connect Adapter for Amazon DynamoDB is optimized for interfacing with that particular database service. The Cross-Org Adapter is meant for retrieving data from other Salesforce orgs rather than external REST APIs.

Thus, the Custom Adapter becomes the right approach, enabling the tailored integration required for effectively working with various REST APIs.