An API page is a Business Central page object of type API that exposes a table as a JSON REST endpoint, used by integrations instead of the user interface.
An API page is a Business Central page object declared with the API page type. It publishes one table as a JSON endpoint over OData v4, with a publisher, group, version and entity name that together form the URL. Standard APIs cover common entities such as customers, vendors, items and invoices, and developers can add their own API pages in an AL extension.
API pages are not opened by users, they are called by applications. On the Business Central side an administrator authorises the calling application: search with Alt+Q for the page that lists registered Microsoft Entra applications, then grant it the permission sets it needs. Pages published as ordinary web services appear on the Web Services page, while an API page delivered by an extension is available as soon as the extension is installed.
An integration reads the purchase invoices of one company. It signs in with OAuth, resolves the company identifier, then calls the standard purchase invoice endpoint with a filter on the vendor number, for example vendorNumber eq 'V10000'. The answer is JSON, one object per invoice, with the fields the API page exposes and an etag value used for later updates.
Frequent errors: calling an endpoint without the company identifier and finding nothing; sending an update without the etag of the record that was read, which the service rejects to avoid overwriting someone else's change; and hitting request limits during a bulk load, which returns a throttling response the caller has to retry after a pause. On the development side, renaming an entity or changing its version changes the URL and breaks every consumer, so treat published names as fixed.
APIs are the supported way to read and write Business Central data from outside, and what an integration can reach stays bounded by the rights of the account it uses. Zentriq Agent and the Zentriq connector for Claude and ChatGPT work through this layer with delegated access: answers only cover data the signed in user may read, and anything they create arrives in Business Central as a draft for approval.
A page or codeunit published as a web service is exposed through the OData or SOAP URL, while an API page is a dedicated page type with a fixed JSON contract and its own api path. For a new integration, the API page is the recommended option.
Either a signed in user with delegated access, or a registered application. In both cases the account must be authorised in Business Central and hold the right permission sets before any data comes back.
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