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

# Generate speech

> Convert text to spoken audio synchronously and get it back inline as base64. `model` and `input` are required; `voice`, `format` (mp3 default), and `speed` are normalized and validated against the model's declared capabilities, and everything in `parameters` is forwarded verbatim to the provider. Output is saved to /v3/files by default and returned with a reusable `file_id`; set `store: false` to opt out.

See the [Audio guide](/build/multimodal/audio) for runnable examples and voices.


## OpenAPI

````yaml post /v3/audio/speech
openapi: 3.1.0
info:
  description: Schema-driven generative API that orchestrates LLM-powered workflows.
  title: Task API
  version: 3.0.0
servers:
  - description: Production
    url: https://api.opper.ai
  - description: Local development
    url: http://localhost:8080
security:
  - BearerAuth: []
tags:
  - description: Schema-driven function management and execution
    name: Functions
  - description: OpenAI-compatible chat completions
    name: Chat
  - description: OpenAI Responses API compatible endpoint
    name: Responses
  - description: Google-compatible interactions endpoint
    name: Interactions
  - description: Model registry and capabilities
    name: Models
  - description: Synchronous image generation
    name: Images
  - description: Text-to-speech and speech-to-text
    name: Audio
  - description: Asynchronous video generation
    name: Videos
  - description: Reusable file storage for media inputs and generated outputs
    name: Files
  - description: Async generation status and downloads
    name: Artifacts
  - description: OpenAI-compatible embeddings
    name: Embeddings
  - description: Recorded HTTP request/response generations
    name: Generations
  - description: System health and status
    name: System
  - description: Roundtable endpoint — fan out a query to multiple LLMs and combine results
    name: Roundtable
  - description: Web search, fetch, and other utility tools
    name: Tools
paths:
  /v3/audio/speech:
    post:
      tags:
        - Audio
      summary: Generate speech (TTS)
      description: >-
        Convert text to spoken audio synchronously and get it back inline as
        base64. `model` and `input` are required; `voice`, `format` (mp3
        default), and `speed` are normalized and validated against the model's
        declared capabilities, and everything in `parameters` is forwarded
        verbatim to the provider. Output is saved to /v3/files by default and
        returned with a reusable `file_id`; set `store: false` to opt out.
      operationId: createSpeech
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SpeechRequest'
        required: true
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SpeechResponse'
          description: Successful response
        '400':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
          description: Bad request
        '401':
          description: Unauthorized - missing or invalid API key
        '500':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
          description: Internal server error
components:
  schemas:
    SpeechRequest:
      properties:
        format:
          type: string
        input:
          type: string
        model:
          type: string
        parameters:
          type: object
        speed:
          type: number
        store:
          description: >-
            Persist the generated audio to /v3/files and return a reusable
            file_id. Defaults to true; set false to skip.
          type: boolean
        voice:
          type: string
      required:
        - model
        - input
      type: object
    SpeechResponse:
      properties:
        audio:
          properties:
            b64_json:
              type: string
            file_id:
              type: string
            mime_type:
              type: string
            url:
              type: string
          type: object
        created:
          type: integer
        id:
          type: string
        model:
          type: string
        usage:
          properties:
            characters:
              type: integer
            cost:
              type: number
          required:
            - cost
            - characters
          type: object
      required:
        - id
        - model
        - created
        - audio
        - usage
      type: object
    ErrorResponse:
      properties:
        error:
          properties:
            code:
              type: string
            details:
              description: Any value
            message:
              type: string
          required:
            - code
            - message
          type: object
        meta:
          type: object
      required:
        - error
      type: object
  securitySchemes:
    BearerAuth:
      bearerFormat: API Key
      description: API key authentication. Pass your API key as a Bearer token.
      scheme: bearer
      type: http

````