> ## Documentation Index
> Fetch the complete documentation index at: https://docs.undrctrl.id/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Understand general concepts, response codes, and authentication strategies.

## Base URL

The UNDRCTRL API is built on REST principles. We enforce HTTPS in every request to improve data security, integrity, and privacy. The API does not support HTTP.

All requests contain the following base URL:

```
https://undrctrl.id/api/v2
```

## Authentication

To authenticate you need to include the `key` in the body parameters of your request, where `ctrl-12345-6789` is your [API Key](https://undrctrl.id/account).

```json theme={null}
{
    "key": "ctrl-12345-6789"
}
```

## Response codes

UNDRCTRL uses standard HTTP codes to indicate the success or failure of your requests.

In general, `2xx` HTTP codes correspond to success, `4xx` codes are for user-related failures, and `5xx` codes are for infrastructure issues.

# API Response Codes and Descriptions

| Status | Description                               |
| ------ | ----------------------------------------- |
| `200`  | Successful request.                       |
| `400`  | Check that the parameters were correct.   |
| `401`  | The API key used was missing.             |
| `403`  | The API key used was invalid.             |
| `404`  | The resource was not found.               |
| `429`  | The rate limit was exceeded.              |
| `5xx`  | Indicates an error with UNDRCTRL servers. |

<Info>Check Error Codes for a comprehensive breakdown of all possible API [errors](/api-reference/errors).</Info>