What are API Pages in Business Central?

API Pages in Microsoft Dynamics 365 Business Central provide a standardized way for external applications and services to interact with Business Central data through REST APIs.

They are designed specifically for integration scenarios.

Instead of exposing the internal UI structure of Business Central, API pages provide a more stable, integration-friendly representation of business data.

For example:

External Application
        ↓
REST API
        ↓
Business Central API Page
        ↓
Business Central Data

Why Are API Pages Important?

Modern organizations rarely operate Business Central in isolation.

It may need to communicate with:

• E-commerce platforms
• CRM systems
• Mobile applications
• Data warehouses
• Payment systems
• Custom applications
• Azure services
• Third-party SaaS platforms

API pages provide a mechanism for these systems to interact with Business Central.

Example Concept

A developer can define an API page with properties such as:

page 50100 CustomerAPI
{
    PageType = API;
    SourceTable = Customer;

    APIPublisher = 'company';
    APIGroup = 'customers';
    APIVersion = 'v1.0';

    EntityName = 'customer';
    EntitySetName = 'customers';
}

The external consumer can then interact with the exposed resource using HTTP methods such as:

GET
POST
PATCH
DELETE

depending on the supported operation and API behavior.

API Page vs Normal Page

This distinction is important.

A normal Business Central page is primarily designed for user interaction through the Business Central client.

An API page is designed for machine-to-machine communication.

That means API pages should be designed around integration contracts rather than user-interface requirements.

API Pages and AL Development

Business Central developers should understand:

• API page structure
• Entity and EntitySet naming
• API versioning
• OData concepts
• Authentication
• Permissions
• JSON payloads
• Error handling
• Integration events
• Data validation

Important Architectural Point

Don't expose every Business Central table directly just because an API is technically possible.

A good integration API should expose the business data and operations that consumers actually need.

For complex integrations, developers should also consider whether standard Business Central APIs, custom APIs, web services, or other integration mechanisms are more appropriate.

Professional Best Practice

Treat your API as a contract.

Once external systems depend on it, changing field names, semantics, or behavior can break integrations.

Therefore:

• Version APIs carefully.
• Avoid unnecessary fields.
• Apply appropriate permissions.
• Validate input.
• Handle failures predictably.
• Design for backward compatibility.

Interview Takeaway

API Pages are Business Central pages specifically designed to expose table data through REST/OData-based APIs for integration scenarios. They provide a structured and developer-friendly contract for external applications to interact with Business Central.