---
title: "Initiate multipart upload"
method: POST
path: "/api/im/files/upload/init"
tags: ["Files"]
---

# Initiate multipart upload

`POST /api/im/files/upload/init`

Initiate multipart upload for large files (10MB-50MB). Returns part URLs.

## Request body

- FilePresignRequest
  - `fileName` string, required — File name (no path separators or null bytes)
  - `fileSize` integer, required — File size in bytes
  - `mimeType` string, required — MIME type (must be in whitelist)

## Response `201`

Multipart upload initiated

## Other responses

- `400` — Invalid request parameters

---

[API](https://skmtc.dev/prismer-ai/apis/prismer-cloud-api.md) · [All operations](https://skmtc.dev/prismer-ai/apis/prismer-cloud-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/prismer-ai/prismer-cloud-api/revisions/7fef0836d17f/schema)