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

# Authentication

> Authenticate REST API requests with an API key.

The REST API accepts an API key in the `x-api-key` header, the `x-api-key` query parameter, or the `Authentication` header. Create and rotate API keys from your Rapida project credentials.

<CodeGroup>
  ```bash x-api-key header theme={null}
  curl --request POST "https://assistant-01.in.rapida.ai/v1/talk/create-phone-call" \
    --header "Content-Type: application/json" \
    --header "x-api-key: $RAPIDA_API_KEY" \
    --data '{
      "assistant": {
        "assistantId": "2227823180112723968",
        "version": "latest"
      },
      "toNumber": "+14155550123"
    }'
  ```

  ```bash x-api-key query parameter theme={null}
  curl --request POST "https://assistant-01.in.rapida.ai/v1/talk/create-phone-call?x-api-key=$RAPIDA_API_KEY" \
    --header "Content-Type: application/json" \
    --data '{
      "assistant": {
        "assistantId": "2227823180112723968",
        "version": "latest"
      },
      "toNumber": "+14155550123"
    }'
  ```

  ```bash Authentication header theme={null}
  curl --request POST "https://assistant-01.in.rapida.ai/v1/talk/create-phone-call" \
    --header "Content-Type: application/json" \
    --header "Authentication: $RAPIDA_API_KEY" \
    --data '{
      "assistant": {
        "assistantId": "2227823180112723968",
        "version": "latest"
      },
      "toNumber": "+14155550123"
    }'
  ```
</CodeGroup>

## Authentication parameters

<ParamField header="x-api-key" type="string">
  API key sent as a request header.
</ParamField>

<ParamField query="x-api-key" type="string">
  API key sent as a query parameter.
</ParamField>

<ParamField header="Authentication" type="string">
  API key sent as an `Authentication` header.
</ParamField>

Use one authentication method per request. Prefer headers for server-side integrations because query parameters can appear in logs.

## Optional headers

<ParamField header="x-auth-id" type="string">
  Optional user identifier to propagate with the request.
</ParamField>

<ParamField header="x-client-source" type="string">
  Optional client source identifier. SDK clients send this automatically.
</ParamField>

## Base URLs

Use the endpoint for the region where your assistant API is hosted.

```text theme={null}
https://assistant-01.in.rapida.ai
https://assistant-01.us.rapida.ai
```

<Warning>
  Do not expose project API keys in browser or mobile clients. Send REST API requests from a trusted backend service.
</Warning>