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

# Render a composition

> Render a composition timeline to a final video — the last step of an end-to-end video pipeline.

An end-to-end video flow with the primitives: generate clips with [Start a generation](/api/start-generation) (type `video`), audio with type `audio`, then compose and render the timeline here. Poll [List renders](/api/list-renders) for the finished video URL.


## OpenAPI

````yaml api-reference/openapi.json POST /v1/renders
openapi: 3.0.3
info:
  title: Flowy App API
  version: 1.3.1
  description: >-
    Run Flowy apps and direct generations programmatically.


    Authenticate with a workspace API key in the `Authorization: Bearer` header.
    A **secret** key (`flowy_…`) is for servers; a **publishable** key
    (`flowy_pk_…`) is browser-safe and only works from its allowlisted domains.
    Every run or generation bills the API key's own workspace credits
    (caller-pays), so a leaked key can never spend another workspace's balance.


    Keys carry **scopes**: `apps:read` (list/inspect apps), `runs:read` (poll
    runs), `runs:write` (start runs), `generations:read` (poll direct
    generations), `generations:write` (start direct generations), `assets:read`
    (list/read workspace assets), and `credits:read` (read the credit balance).
    A request that needs a scope the key doesn't hold returns `403`.


    A published (public) app is runnable by any key; a private app is runnable
    only by a key of its own workspace.
servers:
  - url: https://apis.tryflowy.ai/genstudio-svc-v2/api
    description: Flowy production API
security:
  - ApiKeyAuth: []
tags:
  - name: Apps
    description: Discover apps and inspect their input/output schema.
  - name: Runs
    description: Start runs and poll for their results.
  - name: Generations
    description: Start direct image/video generations and poll for their results.
  - name: Assets
    description: Browse the workspace's asset library (uploads + generated media).
  - name: Credits
    description: Read the workspace's credit balance.
  - name: Spec
    description: The machine-readable OpenAPI document.
paths:
  /v1/renders:
    post:
      tags:
        - Renders
      summary: Render a composition to video
      description: >-
        Render a composition timeline (Remotion project JSON) to a final video —
        the last step of an end-to-end video pipeline (async).
      operationId: startRender
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - project
              properties:
                project:
                  type: object
                  description: The composition timeline
                project_id:
                  type: string
                workspace_id:
                  type: string
      responses:
        '202':
          description: Render started
components:
  securitySchemes:
    ApiKeyAuth:
      type: http
      scheme: bearer
      bearerFormat: flowy_*
      description: >-
        A workspace API key. Secret keys (`flowy_…`) are server-side — keep them
        private. Publishable keys (`flowy_pk_…`) are browser-safe but only work
        from their allowlisted domains.

````