> ## 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](/api-v2/post/tts).

For one model, use `GET /v2/tts/models/:id`.

<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.
</Note>

***

## Headers

<ParamField header="authorization" type="string" required>
  Your API key.
</ParamField>

***

## Response

<ResponseField name="models" type="array">
  Array of model manifests.

  <Expandable title="Model fields">
    <ResponseField name="id" type="string">
      Model identifier, for example `btts-3`. Same value as the `x-model` header.
    </ResponseField>

    <ResponseField name="encodings" type="string[]">
      Supported audio codecs. Pass one as `audio.encoding`.
    </ResponseField>

    <ResponseField name="sample_rates" type="number[]">
      Supported PCM sample rates in Hz. `mulaw` is fixed at 8000 regardless of this list.
    </ResponseField>

    <ResponseField name="containers" type="string[]">
      Supported byte framings (`raw`, `wav`).
    </ResponseField>

    <ResponseField name="controls" type="object">
      Supported voice controls and their allowed ranges. Each entry is an object with `min` and `max`.
    </ResponseField>
  </Expandable>
</ResponseField>

<ResponseExample>
  ```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"
    }
  }
  ```
</ResponseExample>

### 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](/llms.txt)