How Can Business Central Be Integrated with External REST APIs Using AL?

Business Central can integrate with external REST APIs using AL's HTTP capabilities. The typical flow involves creating an HttpClient, constructing an HttpRequestMessage when more control is required, configuring headers, sending the request, checking the response, and processing the returned JSON.

For example, an integration may retrieve customer information from an external service, submit an order to a third-party system, or synchronize inventory information. JSON payloads can be handled using Business Central's JSON data types such as JsonObject, JsonArray, and JsonToken.

Production integrations require considerably more than simply calling an endpoint. Developers should design for authentication, timeout handling, HTTP status codes, retries, throttling, idempotency, logging, validation, pagination, and API versioning. Sensitive credentials should not be hard-coded in AL. Authentication architecture should use the mechanism supported by the external API and Business Central's secure configuration capabilities.

For larger integrations, developers should also consider whether the API call should happen synchronously during a user transaction or asynchronously through a background process. Long-running or unreliable external calls inside interactive transactions can negatively affect user experience and transaction reliability.

Expert takeaway: A REST integration is successful when it remains reliable under network failures, duplicate requests, API throttling, authentication changes, partial failures, and schema evolution. Good AL development therefore requires integration architecture—not just HTTP syntax.