---
title: "POST assets instances_init_multipart_upload"
method: POST
path: "/api/v1/assets/init_multipart_upload"
---

# POST assets instances_init_multipart_upload

`POST /api/v1/assets/init_multipart_upload`

## Request

- Base URL: `https://app.onecodex.com`
- URL: `https://app.onecodex.com/api/v1/assets/init_multipart_upload`
- Auth: API key in header `X-API-Key`

## Response `200`

OK

- object
  - `callback_url` string, required: The relative URL to POST to after the multipart upload completes in order to confirm the upload and create the asset.
  - `file_id` string, required: A unique identifier for the multipart upload. Use as the object storage key prefix when uploading file parts.
  - `s3_bucket` string, required: The object storage bucket to which file parts should be uploaded.
  - `upload_aws_access_key_id` string, required: An AWS access key ID with permission to upload to `s3_bucket`.
  - `upload_aws_secret_access_key` string, required: The AWS secret access key paired with `upload_aws_access_key_id`.

## Changes

- **2026-11-03** `3be5a5f9bf7d`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/onecodex/apis/one-codex-api-v1/changes/api/v1/assets/init_multipart_upload/post.md)

---

[API](https://skmtc.dev/onecodex/apis/one-codex-api-v1.md) - [All operations](https://skmtc.dev/onecodex/apis/one-codex-api-v1/llms.txt) - [OpenAPI document](https://skmtc.dev/onecodex/apis/one-codex-api-v1/revisions/3be5a5f9bf7d?raw)