> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.vapi.ai/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.vapi.ai/_mcp/server.

# Gandr

> Wire Gandr, a text to speech API for voice agents, into Vapi with the custom-voice provider and Custom Credentials.

Gandr is a text to speech API built for voice agents. It reads numbers, dates, order IDs and addresses correctly, one engine speaks 23 languages with six voices, and every render carries an inaudible watermark. Audio streams back as it is generated.

Gandr's `/v1/vapi` endpoint implements the custom-voice contract described in the [Custom TTS guide](/customization/custom-voices/custom-tts): it reads the nested `message` envelope, honours the requested `sampleRate` (8000, 16000, 22050, 24000 or 44100), and returns raw 16-bit little-endian mono PCM.

> **Note**
>
> A Gandr account and API key are required.

#### Create a Gandr key

Sign up at [gandr.ai](https://gandr.ai) and copy your API key.

#### Store the key in a Custom Credential

In the [Vapi Dashboard](https://dashboard.vapi.ai), create a **Custom Credential** holding your Gandr key, following [server authentication](/server-url/server-authentication), so the key never travels in the assistant config.

#### Add Gandr as the voice provider

In the assistant config, set the voice provider to `custom-voice` and point it at Gandr:

```json
{
  "voice": {
    "provider": "custom-voice",
    "server": {
      "url": "https://tts.gandr.ai/v1/vapi",
      "credentialId": "<your-custom-credential-id>",
      "timeoutSeconds": 10
    }
  }
}
```

#### Pick a voice and language

Gandr's stock voices are `gandr-ava`, `gandr-dane`, `gandr-jenny`, `gandr-leo`, `gandr-lewis` and `gandr-mia`. The default is an English female voice. Any of the 23 languages can be set per request, independent of the voice.

#### Test the call

Run a test call in the dashboard. If you hear audio, you are done. If the call times out, check that the Gandr key in the Custom Credential is active and that `https://tts.gandr.ai/v1/vapi` answers.

## Pricing

See [Gandr's pricing page](https://gandr.ai/pricing/) for current plan and usage pricing.

Full API reference: [gandr.ai/docs](https://gandr.ai/docs).