# Authentication

## API Key

To authenticate your API requests, include your API key in the request header:

```
API-KEY: your_api_key
```

You can find your API key in your Alli dashboard under the Settings menu (General tab).

## User Identification

### User ID

Specify a user by including a user ID in the `OWN-USER-ID` header. This can be either:

* An existing user ID - identifies a previously created user
* A new user ID - Alli will automatically create a new user with this ID

All future API calls with the same `OWN-USER-ID` will be treated as coming from the same user.

### Email Information

You can associate an email address with a user by including it in the `USER-EMAIL` header.

### Non-ASCII Character Limitations

The `OWN-USER-ID` header cannot contain non-ASCII characters. If your user ID includes non-ASCII characters, encode it to base64 and use the format:

```
OWN-USER-ID: base64:CONVERTED_ID
```

User ID and email information can be viewed in the Customers section of your Alli dashboard.

Example Headers

```
OWN-USER-ID: 5f1234567a409876c082487
USER-EMAIL: user_1@email.com
```

## Agent Information

To make API calls using a specific agent's information, include the agent's email in the `AGENT-EMAIL` header. When you include a logged-in agent's email in the `AGENT-EMAIL` header, the API call will use that agent's information.

Example Headers

```
AGENT-EMAIL: agent_1@email.com
```