> For the complete documentation index, see [llms.txt](https://docs.ecommerce.seb.ee/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ecommerce.seb.ee/integration/merchant-api/response-handling.md).

# Response Handling

When processing API responses, it is important to distinguish between:

* **HTTP Status Codes** – Indicates whether the request was successfully processed from a technical perspective.
* **Error Codes** – Provides additional details when a request cannot be processed successfully.
* **Payment Statuses and Status Reasons** – Indicates the business outcome of a payment operation.

### HTTP Status Codes

HTTP status codes indicate the outcome of the API request itself.

| Status Range | Description                                                                                                                                                          |
| ------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `2xx`        | The request was successfully received and processed.                                                                                                                 |
| `4xx`        | The request could not be processed due to an issue with the request, such as validation errors, authentication failures, insufficient permissions, or rate limiting. |
| `5xx`        | The request could not be completed due to an internal system error or temporary service unavailability.                                                              |

A successful `2xx` response only indicates that the request was processed successfully. It does **not** necessarily mean that the payment itself was successful, for this the payment statuses are used.

#### Error Codes

For non-successful requests, the response contains one or more error codes describing the specific reason for the failure.

Typical examples include:

* Invalid or missing request parameters.
* Authentication or authorization failures.
* Rate limit violations.
* Other business or technical validation errors.

Error codes should be used together with the HTTP status code when implementing error handling and troubleshooting logic.

### Payment Statuses

For payment-related operations, the payment outcome is communicated through the **payment status** returned in the API response or delivered through callback notifications.

A successful HTTP response may indicate a payment that is **pending**, **successful**, or **failed**, depending on the outcome of the payment processing. Applications should therefore use the payment status as the authoritative source for determining the payment outcome.

#### Payment Status Reasons

Payment statuses may include an accompanying **status reason** that provides additional context about why a payment reached its current state.

Status reasons indicate:

* Business-level outcomes, such as insufficient funds, expired cards, suspected fraud, issuer declines, or network declines.
* Processing and communication issues, such as issuer unavailability, network interruptions, or temporary processing failures.

Status reasons are intended to support payment handling logic, troubleshooting, reporting, and customer communication where appropriate.


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