---
title: "Run Hedra Character 3 (hedra-character-3)"
method: POST
path: "/models/hedra-character-3"
tags: ["Run a model"]
---

# Run Hedra Character 3 (hedra-character-3)

`POST /models/hedra-character-3`

## Request

- Base URL: `https://api.hedra.com/v3`
- URL: `https://api.hedra.com/v3/models/hedra-character-3`
- Auth: one of:
  - API key in header `Authorization`
  - HTTP bearer

Hedra's latest longform avatar model, audio to video will full multi-language support. Perfect for talking and singing video with speaker selection up to 10 minutes long.

Submits an asynchronous job and returns `202` with a job id. Fetch the result at `GET /v3/jobs/{job_id}` — each item in its `outputs[]` follows the `OutputItem` schema — or track progress via `GET /v3/jobs/{job_id}/status` / the SSE stream at `GET /v3/jobs/{job_id}/stream`.

## Headers

- `Idempotency-Key` string

## Request body

- SubmitBodyHedraCharacter3
  - `input` InputHedraCharacter3, required: Model-specific inputs for `hedra-character-3`.
    - `num_outputs` 1: Number of outputs generated per job. Only 1 is supported.
    - `prompt` string, required: Generation prompt.
    - `aspect_ratio` '1:1' | '4:3' | '3:4' | '16:9' | '9:16' | '9:21' | '21:9', required: Output aspect ratio.
    - `resolution` '540p' | '720p' | '1080p', required: Output resolution.
    - `duration_ms` integer: Duration in ms. At most 600000.
    - `start_image` union, required: Start frame. At most 10.4 MB.
      - object: A file uploaded via POST /v3/files, referenced by the returned url.
        - `source` 'url', required
        - `url` string, uri, required: A URL returned by POST /v3/files.
      - object: An existing asset you own, referenced by its id.
        - `source` 'asset', required
        - `asset_id` string, required: The asset's id (`asset_<uuid>`), as issued by the server — a completed generation publishes one per output as `outputs[].asset_id`. Do not construct one or derive it from any other id.
    - `audio` union, required: Driving audio: a single reference, or a list of references for multi-speaker generation — one audio per speaker, played in list order. 1 to 4 audio files, each from 0.5s to 600s and at most 104.8 MB.
      - union
        - object: A file uploaded via POST /v3/files, referenced by the returned url.
          - `source` 'url', required
          - `url` string, uri, required: A URL returned by POST /v3/files.
        - object: An existing asset you own, referenced by its id.
          - `source` 'asset', required
          - `asset_id` string, required: The asset's id (`asset_<uuid>`), as issued by the server — a completed generation publishes one per output as `outputs[].asset_id`. Do not construct one or derive it from any other id.
      - union[]
        - union
          - object: A file uploaded via POST /v3/files, referenced by the returned url.
            - `source` 'url', required
            - `url` string, uri, required: A URL returned by POST /v3/files.
          - object: An existing asset you own, referenced by its id.
            - `source` 'asset', required
            - `asset_id` string, required: The asset's id (`asset_<uuid>`), as issued by the server — a completed generation publishes one per output as `outputs[].asset_id`. Do not construct one or derive it from any other id.
    - `bounding_box_target` union: Speaker position(s) in the start frame, as normalized [x, y] image coordinates (0-1 from the top-left).
      - unknown[]
        - unknown
      - array[]
        - unknown[]
          - unknown
  - `webhook` string, uri, nullable: URL to receive a signed completion webhook.

## Response `202`

Accepted. The job runs asynchronously; poll `status_url` / `result_url` from the ack.

- SubmitResponse
  - `job_id` string, required: This job's id — server-issued, and opaque.
  - `model` string, required: The resolved model id this job runs on.
  - `status` 'IN_QUEUE' | 'IN_PROGRESS' | 'COMPLETED' | 'FAILED', required: The four states a job can be in.
  - `status_url` string, required: Path of this job's status monitor: poll GET /v3/jobs/{job_id}/status for status, progress, and the estimated completion time.
  - `result_url` string, required: Path of the job resource itself: GET /v3/jobs/{job_id} returns the result envelope, including the outputs once it completes. Also the value of this response's `Location` header.
  - `estimated_completion_at` string, date-time, nullable: ISO-8601 instant this job is estimated to finish, as of this response. Null when no estimate is available yet, and when the job has already finished. The estimate can change while the job runs: poll `GET /v3/jobs/{job_id}/status` for the current one.

## Other responses

- `400`: Invalid or failed-validation request.
- `401`: Authentication failed: missing, malformed, or invalid credentials.
- `402`: The API wallet cannot cover this request. `error.billing` carries the balance, the price, and where to add funds.
- `403`: Insufficient scope or plan.
- `404`: Resource not found.
- `422`: Moderation refused the request's content.
- `429`: Rate limit exceeded.
- `500`: Internal error.

## Changes

- **2026-10-16** `06692d16e78a`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/hedra-labs/apis/hedra-api/changes/models/hedra-character-3/post.md)

---

[API](https://skmtc.dev/hedra-labs/apis/hedra-api.md) - [All operations](https://skmtc.dev/hedra-labs/apis/hedra-api/llms.txt) - [OpenAPI document](https://skmtc.dev/hedra-labs/apis/hedra-api/revisions/6ef35a11cefe?raw)