---
title: "POST /create-asset"
method: POST
path: "/create-asset"
---

# POST /create-asset

`POST /create-asset`

## Request

- Base URL: `https://api.retellai.com`
- URL: `https://api.retellai.com/create-asset`
- Auth: HTTP bearer

Upload an image or audio asset. Audio is normalized to headerless mono PCM16 at 24 kHz and can be referenced by `custom_on_hold_music_asset_id` on warm and agentic-warm transfer options. Accepted audio formats are MP3, WAV, WebM, OGG, M4A, AAC, and FLAC. The maximum upload size is 10 MB and audio duration is limited to 210 seconds.

## Request body `multipart/form-data`

- object
  - `file` string, binary, required: Image or audio file to upload. Images support PNG, JPEG, GIF, WebP, and SVG. Audio supports MP3, WAV, WebM, OGG, M4A, AAC, and FLAC. Maximum size is 10 MB; audio is limited to 210 seconds.

## Response `201`

Successfully created asset.

- Asset
  - `asset_id` string: Unique identifier for the asset.
  - `file_name` string: Stored file name. Uploaded audio is normalized to headerless PCM and uses a `.pcm` extension.
  - `content_type` string: MIME type of the asset.
  - `file_size` number: File size in bytes.
  - `url` string: CDN URL to access the asset.
  - `created_timestamp` number: Unix timestamp of when the asset was created.

## Other responses

- `400`: Bad Request
- `401`: Unauthorized
- `429`: Too Many Requests
- `500`: Internal Server Error

## Changes

- **2026-10-16** `ca41f0dbb297`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/retellai/apis/retell-sdk/changes/create-asset/post.md)

---

[API](https://skmtc.dev/retellai/apis/retell-sdk.md) - [All operations](https://skmtc.dev/retellai/apis/retell-sdk/llms.txt) - [OpenAPI document](https://skmtc.dev/retellai/apis/retell-sdk/revisions/e482acaa292c?raw)