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

# Transcribe a completed audio file

> OpenAI-compatible file transcription with `openai/gpt-transcribe`.
Set `stream: true` to receive transcript events over SSE. Successful
requests are billed at $0.0045 per audio minute.




## OpenAPI

````yaml /openapi.yaml post /v1/audio/transcriptions
openapi: 3.1.0
info:
  title: Impossibl AI API
  version: 0.0.1
  description: >
    The Impossibl AI API is one API for all AI providers, OpenAI-compatible
    across OpenAI,

    Anthropic, Google, xAI, and more (`GET /v1/models` lists the full catalog),

    billed from a prepaid credit balance.


    Provider usage is billed at provider list prices with no usage markup.

    Prepaid credit purchases charge a separate fixed 5% platform fee before tax.


    **Agent quickstart**

    1. `POST /v1/accounts` — create a funded account; you get an API key and a
       signup-bonus balance in one call (no human step required).
    2. Call `POST /v1/chat/completions`, `POST /v1/responses`, or
       `POST /v1/audio/transcriptions` with
       `Authorization: Bearer <key>` and a `provider/model` id from `GET /v1/models`.
    3. Credits are deducted per request by token or audio-duration usage; check
    `GET /v1/account`.
servers:
  - url: https://api.impossibl.com
    description: Production
  - url: http://localhost:8787
    description: Local dev
security:
  - BearerKey: []
paths:
  /v1/audio/transcriptions:
    post:
      summary: Transcribe a completed audio file
      description: |
        OpenAI-compatible file transcription with `openai/gpt-transcribe`.
        Set `stream: true` to receive transcript events over SSE. Successful
        requests are billed at $0.0045 per audio minute.
      operationId: createAudioTranscription
      requestBody:
        required: true
        content:
          multipart/form-data:
            schema:
              type: object
              required:
                - model
                - file
              properties:
                model:
                  type: string
                  enum:
                    - openai/gpt-transcribe
                file:
                  type: string
                  format: binary
                  maxLength: 26214400
                  description: >-
                    Completed audio file accepted by the OpenAI Transcriptions
                    API.
                prompt:
                  type: string
                  description: Unstructured context about the recording.
                keywords[]:
                  type: array
                  items:
                    type: string
                  description: >-
                    Literal terms expected in the recording. Repeat this
                    multipart field for multiple terms.
                languages[]:
                  type: array
                  items:
                    type: string
                  description: >-
                    Expected language codes. Repeat this multipart field for
                    multiple languages.
                response_format:
                  type: string
                  enum:
                    - json
                    - text
                  default: json
                stream:
                  type: boolean
                  default: false
      responses:
        '200':
          description: >-
            A completed transcript object, or transcript events when `stream` is
            true.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AudioTranscription'
            text/plain:
              schema:
                type: string
            text/event-stream:
              schema:
                type: string
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '402':
          $ref: '#/components/responses/InsufficientCredits'
        '404':
          $ref: '#/components/responses/UnknownModel'
        '413':
          $ref: '#/components/responses/PayloadTooLarge'
        '502':
          $ref: '#/components/responses/UpstreamError'
        '503':
          $ref: '#/components/responses/ProviderNotConfigured'
components:
  schemas:
    AudioTranscription:
      type: object
      required:
        - text
        - languages
      properties:
        text:
          type: string
        languages:
          type: array
          items:
            type: object
            properties:
              code:
                type: string
        usage:
          type: object
          description: Present when OpenAI reports duration usage.
          properties:
            type:
              type: string
              const: duration
            seconds:
              type: number
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            message:
              type: string
            type:
              type: string
              description: >-
                One of authentication_error, invalid_request_error,
                insufficient_quota, upstream_error, provider_not_configured.
  responses:
    BadRequest:
      description: Malformed request (bad JSON, or missing required fields).
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: '`model` and `messages` are required'
              type: invalid_request_error
    Unauthorized:
      description: Missing or invalid API key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: Invalid API key
              type: authentication_error
    InsufficientCredits:
      description: The account's credit balance is empty. Top up to continue.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: Insufficient credits. Top up to continue.
              type: insufficient_quota
    UnknownModel:
      description: The requested `model` id is not in the registry (see GET /v1/models).
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: 'Unknown model: foo/bar'
              type: invalid_request_error
    PayloadTooLarge:
      description: The uploaded audio file exceeds 25 MB.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: Maximum file size is 25 MB.
              type: invalid_request_error
              param: file
              code: file_too_large
    UpstreamError:
      description: The upstream provider returned an error.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: 'permission-denied: ...'
              type: upstream_error
    ProviderNotConfigured:
      description: The provider for this model has no API key configured on the gateway.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error:
              message: 'Provider not configured: missing OPENAI_API_KEY'
              type: provider_not_configured
  securitySchemes:
    BearerKey:
      type: http
      scheme: bearer
      description: Gateway API key (`imp-rt-...`) from POST /v1/accounts or /v1/keys.

````