> ## Documentation Index
> Fetch the complete documentation index at: https://docs.deliverykey.com/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 DeliveryKey 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:

## Authentication

To authenticate you need to add an Authorization header with the contents of the header being Bearer `dlk_123456789` where `dlk_123456789` is your API Key.

```
Authorization: Bearer dlk_123456789
```

## Response codes

DeliveryKey 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.