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

# List TTS Models

> List what each TTS model supports.

## Overview

Lists the encodings, sample rates, containers, and controls each model supports. Use it to build a picker, validate a request before sending it, or check what a new model added.

You do not choose a model — the voice you pass decides it. It comes back in the `x-model` header on [Synthesize Speech](https://docs.bland.ai/api-v2/post/tts.md).

For one model, use `GET /v2/tts/models/:id`. For unauthenticated, OpenAI-compatible discovery, use [List Models (Public)](https://docs.bland.ai/api-v2/get/models.md).

> [!NOTE]
>
> Prefer **`btts-3` or newer**. `expressiveness` and `stability` are calibrated for it,
> and 48 kHz is the rate it renders natively. `btts-2` is listed because it still
> synthesizes, but the controls are not tuned for it.

***

## Headers

**authorization** `string` *required*

Your API key.

***

## Response

**models** `array`

Array of model manifests.

**Model fields**

**id** `string`

Model identifier, for example `btts-3`. Same value as the `x-model` header.

**encodings** `string[]`

Supported audio codecs. Pass one as `audio.encoding`.

**sample\_rates** `number[]`

Supported PCM sample rates in Hz. `mulaw` is fixed at 8000 regardless of this list.

**containers** `string[]`

Supported byte framings (`raw`, `wav`).

**controls** `object`

Supported voice controls and their allowed ranges. Each entry is an object with `min` and `max`.

```json Response theme={null}
{
  "models": [
    {
      "id": "btts-3",
      "encodings": ["pcm_s16le", "mulaw"],
      "sample_rates": [8000, 16000, 24000, 44100, 48000],
      "containers": ["raw", "wav"],
      "controls": {
        "expressiveness": { "min": 0, "max": 1 },
        "stability": { "min": 0, "max": 1 }
      }
    },
    {
      "id": "btts-2",
      "encodings": ["pcm_s16le", "mulaw"],
      "sample_rates": [8000, 16000, 24000, 44100, 48000],
      "containers": ["raw", "wav"],
      "controls": {
        "expressiveness": { "min": 0, "max": 1 },
        "stability": { "min": 0, "max": 1 }
      }
    }
  ]
}
```

```json Not found (GET /v2/tts/models/:id) theme={null}
{
  "error": {
    "code": "not_found",
    "message": "Unknown model: btts-9"
  }
}
```

### Error codes

| Code | HTTP | Meaning |
| - | - | - |
| `not_found` | 404 | `GET /v2/tts/models/:id` was called with an unknown model ID. |

***

Docs for agents: [llms.txt](https://docs.bland.ai/llms.txt)


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