> For the complete documentation index, see [llms.txt](https://docs.zaui.com/io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zaui.com/io/appendixes/http-status-codes.md).

# HTTP Status Codes

{% hint style="info" %}
If you're experiencing return codes of 503 from our platform, you are exceeding the allows API throttle limits.  Please rerfer our section under "Getting Started" an how to handle 503 errors.
{% endhint %}

| Code | Reason       | Description                                        | Recommended Action                                                                             |
| ---- | ------------ | -------------------------------------------------- | ---------------------------------------------------------------------------------------------- |
| 200  | Status OK    | Request executed without error                     | None                                                                                           |
| 400  | BAD REQUEST  | Invalid request                                    | Check for mal-formed XML                                                                       |
| 401  | UNAUTHORIZED | Authenticated for the request has failed           | Check the required authentication requirements                                                 |
| 404  | NOT FOUND    | Requested API routine is not an implemented method | Check the naming of the inbound request                                                        |
| 503  | UNAVAILABLE  | Throttle rate limit has been exceeded              | Retry using exponential back off. You need to slow down the rate at which are sending requests |