---
title: "Initiate multipart upload for vault file"
method: POST
path: "/vault/{id}/multipart/init"
tags: ["Vaults"]
---

# Initiate multipart upload for vault file

`POST /vault/{id}/multipart/init`

## Request

- Base URL: `https://api.case.dev`
- URL: `https://api.case.dev/vault/{id}/multipart/init`
- Auth: HTTP bearer

Initiate a multipart upload for large files (>5GB). Single PUT uploads are capped at 5GB; multipart default max is 16GB (configurable). Multipart uploads are supported in production. Returns an uploadId and object metadata. Use part URLs endpoint to upload parts and complete endpoint to finalize.

## Path parameters

- `id` string, required

## Request body

- object
  - `filename` string, required: Name of the file to upload
  - `contentType` string, required: MIME type of the file
  - `sizeBytes` integer, required: File size in bytes (required, default max 16GB). Configure via VAULT_MULTIPART_MAX_FILE_SIZE_BYTES.
  - `partSizeBytes` integer: Multipart part size in bytes (min 5MB, max 5GB). Defaults to 64MB.
  - `metadata` object: Additional metadata to associate with the file
  - `file_origin` object: Optional client-defined provenance metadata. Returned with the object and queryable through the object-list API.
  - `auto_index` boolean: Whether to automatically process and index the file for search
  - `is_ai_generated` boolean: Marks the file as AI-generated work product (e.g. uploaded by an agent) rather than a user-provided source document. Persisted on the object and returned by object listings so clients can distinguish provenance.
  - `path` string: Optional folder path, excluding the filename, for hierarchy preservation

## Response `200`

Multipart upload initiated

- object
  - `objectId` string
  - `uploadId` string
  - `s3Key` string
  - `partSizeBytes` integer
  - `partCount` integer
  - `file_origin` object, nullable: Client-defined provenance metadata associated with the file
  - `next_step` string

## Changes

- **2026-10-16** `a21d188f4b21`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/casemark/apis/case-dev-api/changes/vault/:id/multipart/init/post.md)

---

[API](https://skmtc.dev/casemark/apis/case-dev-api.md) - [All operations](https://skmtc.dev/casemark/apis/case-dev-api/llms.txt) - [OpenAPI document](https://skmtc.dev/casemark/apis/case-dev-api/revisions/9a3245c00044?raw)