Cartesia Voice Changer API

openapi: 3.0.3
info:
  title: Cartesia Agents Voice Changer API
  description: 'The Cartesia REST API for real-time voice AI - text-to-speech and voice-changer generation (single-shot bytes or Server-Sent Events), batch speech-to-text transcription, voice management and cloning, audio infill, custom datasets, pronunciation dictionaries, API keys and scoped access tokens, the Voice Agents platform (agents, calls, call batches, phone numbers, telephony providers, webhooks, deployments, knowledge base documents/folders, and evaluation metrics), and usage reporting. All requests require a `Cartesia-Version` header and an `Authorization: Bearer` API key (`sk_car_...`) or short-lived access token. The lowest-latency, streaming surface for TTS and STT is a separate WebSocket protocol documented in the companion AsyncAPI document at asyncapi/cartesia-ai-asyncapi.yml.'
  version: '2026-03-01'
  contact:
    name: Cartesia
    url: https://cartesia.ai
  license:
    name: API documentation - Cartesia Terms of Service
    url: https://cartesia.ai/terms-of-service
servers:
- url: https://api.cartesia.ai
  description: Cartesia production API
security:
- bearerAuth: []
tags:
- name: Voice Changer
  description: Transform speech into a different target voice.
paths:
  /voice-changer/bytes:
    post:
      operationId: voiceChangerBytes
      tags:
      - Voice Changer
      summary: Voice Changer (Bytes)
      description: Transforms an uploaded speech recording into a different target voice, returning raw audio bytes.
      parameters:
      - $ref: '#/components/parameters/CartesiaVersion'
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/VoiceChangerRequest'
      responses:
        '200':
          description: Transformed audio.
          content:
            audio/*:
              schema:
                type: string
                format: binary
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
  /voice-changer/sse:
    post:
      operationId: voiceChangerSse
      tags:
      - Voice Changer
      summary: Voice Changer (SSE)
      description: Transforms an uploaded speech recording into a different target voice, streamed as Server-Sent Events.
      parameters:
      - $ref: '#/components/parameters/CartesiaVersion'
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              $ref: '#/components/schemas/VoiceChangerRequest'
      responses:
        '200':
          description: Server-Sent Events stream of transformed audio chunks.
          content:
            text/event-stream:
              schema:
                type: string
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  responses:
    Unauthorized:
      description: Missing, invalid, or expired API key / access token.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    ValidationError:
      description: The request payload failed validation.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  schemas:
    VoiceChangerRequest:
      type: object
      required:
      - clip
      - voice_id
      - output_format[container]
      - output_format[sample_rate]
      properties:
        clip:
          type: string
          format: binary
          description: Source speech recording to transform.
        voice_id:
          type: string
        output_format[container]:
          type: string
          enum:
          - raw
          - wav
          - mp3
        output_format[sample_rate]:
          type: integer
          enum:
          - 8000
          - 16000
          - 22050
          - 24000
          - 44100
          - 48000
        output_format[encoding]:
          type: string
          enum:
          - pcm_f32le
          - pcm_s16le
          - pcm_mulaw
          - pcm_alaw
        output_format[bit_rate]:
          type: integer
          enum:
          - 32000
          - 64000
          - 96000
          - 128000
          - 192000
    Error:
      type: object
      properties:
        title:
          type: string
        message:
          type: string
        error_code:
          type: string
        status_code:
          type: integer
        doc_url:
          type: string
        request_id:
          type: string
  parameters:
    CartesiaVersion:
      name: Cartesia-Version
      in: header
      required: true
      description: API version date, e.g. 2026-03-01.
      schema:
        type: string
        example: '2026-03-01'
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: sk_car_... API key or short-lived access token
      description: 'Cartesia API key (sk_car_...) or a short-lived access token minted via POST /access-token, passed as Authorization: Bearer <token>. Every request also requires the Cartesia-Version header.'