fal Streaming API

openapi: 3.2.0
info:
  title: fal Model Streaming API
  description: 'The fal Model APIs are a unified queue-based REST surface for invoking 1,000+ production generative image, video, audio, and multimodal models hosted on fal''s GPU inference infrastructure. Clients submit a job to `https://queue.fal.run/{model-owner}/{model-name}`, then either poll for status and result, subscribe via webhook, or stream incremental progress.

    '
  version: v1
  contact:
    name: fal Support
    url: https://fal.ai/support
  license:
    name: fal Terms of Service
    url: https://fal.ai/legal/terms-of-service
servers:
- url: https://queue.fal.run
  description: Production queue endpoint
security:
- FalKeyAuth: []
tags:
- name: Streaming
  description: Server-sent streaming of incremental model output.
paths:
  /{model_owner}/{model_name}/stream:
    post:
      summary: Stream Model Inference Output
      description: 'Synchronous streaming endpoint that emits Server-Sent Events as the model produces progressive output (tokens, intermediate frames, diffusion steps). Useful for chatty multimodal models and live previews.

        '
      operationId: streamRequest
      tags:
      - Streaming
      parameters:
      - $ref: '#/components/parameters/ModelOwner'
      - $ref: '#/components/parameters/ModelName'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InferenceRequest'
      responses:
        '200':
          description: 'SSE stream of `event: progress` and `event: output` messages.'
          content:
            text/event-stream:
              schema:
                type: string
                description: Server-Sent Events stream.
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
components:
  schemas:
    ErrorResponse:
      type: object
      properties:
        detail:
          oneOf:
          - type: string
          - type: array
            items:
              type: object
    InferenceRequest:
      type: object
      description: 'Model-specific JSON payload. Each model defines its own schema in the model gallery (https://fal.ai/models). Common fields include `prompt`, `image_url`, `seed`, `num_inference_steps`, and `guidance_scale`.

        '
      additionalProperties: true
      properties:
        prompt:
          type: string
          description: Natural-language prompt describing the desired output.
        image_url:
          type: string
          format: uri
          description: Optional reference image URL (commonly an `https://v3.fal.media/...` asset).
        seed:
          type: integer
          description: Optional integer seed for deterministic outputs.
  responses:
    ValidationError:
      description: The model input failed validation against the per-model schema.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
    Unauthorized:
      description: 'Missing or invalid `Authorization: Key …` header.'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
  parameters:
    ModelName:
      name: model_name
      in: path
      required: true
      description: Model identifier (e.g. `flux/schnell`, `kling-2.5/text-to-video`, `veo-3`).
      schema:
        type: string
    ModelOwner:
      name: model_owner
      in: path
      required: true
      description: Owning organization of the model (e.g. `fal-ai`, `black-forest-labs`).
      schema:
        type: string
  securitySchemes:
    FalKeyAuth:
      type: apiKey
      in: header
      name: Authorization
      description: 'Pass the fal API key as `Authorization: Key $FAL_KEY`. Keys are issued from the fal dashboard at https://fal.ai/dashboard/keys.

        '