curl -X POST 'https://api.openai.com/v1/files' \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -F 'file=@sample.bin' \
  -F 'purpose=assistants'

# POST /files (OpenAI API)
Base URL: https://api.openai.com/v1
Auth: Authorization; OpenAI API key; required.
Request formats: multipart/form-data.
Last verified: 2026-10-20

> Upload file

## Critical Gotchas
* The Responses API is the primary interface for new text and tool workflows; Chat Completions remains a separate compatibility API.
* Audio transcription uploads use multipart form data rather than a JSON request body.

## cURL
curl -X POST 'https://api.openai.com/v1/files' \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -F 'file=@sample.bin' \
  -F 'purpose=assistants'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| file | body | string | Yes | The File object (not file name) to be uploaded.  |
| purpose | body | string | Yes | The intended purpose of the uploaded file. One of: - `assistants`: Used in th... |
| expires_after | body | object | No | The expiration policy for a file. By default, files with `purpose=batch` expi... |

## Response example
{"id":"string","bytes":0}

---
Need an API key? Get one at https://platform.openai.com/api-keys

POST

POST /files — OpenAI API

OpenAI API key (required); https://api.openai.com/v1

OpenAI API

Upload file

Base URL: https://api.openai.com/v1
Auth: Authorization: Bearer <OPENAI_API_KEY>
Last verified: 2026-10-20 · upstream hash matched

Actions Try in browser→

Agents: curl -H "Accept: text/markdown" this URL
→ 234 tokens · Vary: Accept

Critical gotchas

The Responses API is the primary interface for new text and tool workflows; Chat Completions remains a separate compatibility API.

Audio transcription uploads use multipart form data rather than a JSON request body.

cURL

curl -X POST 'https://api.openai.com/v1/files' \  -H "Authorization: Bearer $OPENAI_API_KEY" \  -F '[email protected]' \  -F 'purpose=assistants'

Parameters

Name	In	Type	Required	Description
file	body	string	Yes	The File object (not file name) to be uploaded.
purpose	body	string	Yes	The intended purpose of the uploaded file. One of: - `assistants`: Used in the Assistants API - `batch`: Used in the Batch API - `fine-tune`: Used for fine-tuning - `vision`: Images used for vision fine-tuning - `user_data`: Flexible file type for any purpose - `evals`: Used for eval data sets
expires_after	body	object	No	The expiration policy for a file. By default, files with `purpose=batch` expire after 30 days and all other files are persisted until they are manually deleted.

Response 200 OK

{
  "id": "string",
  "bytes": 0,
  "created_at": 0,
  "expires_at": 0,
  "filename": "string",
  "object": "file",
  "purpose": "assistants",
  "status": "uploaded",
  "status_details": "string"
}

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