curl -X POST 'https://api.openai.com/v1/conversations/conv_123/items?include=example' \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "items": [
    {
      "role": "user",
      "content": "example-content",
      "phase": "commentary",
      "type": "message"
    }
  ]
}'

# POST /conversations/{conversation_id}/items (OpenAI API)
Base URL: https://api.openai.com/v1
Auth: Authorization; OpenAI API key; required.
Request formats: application/json.
Last verified: 2026-10-20

> Create items

## 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/conversations/conv_123/items?include=example' \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "items": [
    {
      "role": "user",
      "content": "example-content",
      "phase": "commentary",
      "type": "message"
    }
  ]
}'

## Parameters
| Name | In | Type | Required | Description |
| :--- | :--- | :--- | :--- | :--- |
| conversation_id | path | string | Yes | The ID of the conversation to add the item to. |
| items | body | object[] | Yes | The items to add to the conversation. You may add up to 20 items at a time.  |
| include | query | string[] | No | Additional fields to include in the response. See the `include` parameter for... |

## Response example
{"object":"list","data":[{}]}

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

POST

POST /conversations/{conversation_id}/items — OpenAI API

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

OpenAI API

Create items

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
→ 259 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/conversations/conv_123/items?include=example' \  -H "Authorization: Bearer $OPENAI_API_KEY" \  -H 'Content-Type: application/json' \  -d '{  "items": [    {      "role": "user",      "content": "example-content",      "phase": "commentary",      "type": "message"    }  ]}'

Parameters

Name	In	Type	Required	Description
conversation_id	path	string	Yes	The ID of the conversation to add the item to.
include	query	string[]	No	Additional fields to include in the response. See the `include` parameter for [listing Conversation items above](https://developers.openai.com/api/reference/resources/conversations/subresources/items/methods/list#%28resource%29%20conversations.items%20%3E%20%28method%29%20list%20%3E%20%28params%29%20default%20%3E%20%28param%29%20include%20%3E%20%28schema%29) for more information.
items	body	object[]	Yes	The items to add to the conversation. You may add up to 20 items at a time.

Response 200 OK

{
  "object": "list",
  "data": [
    {
      "type": "message",
      "id": "string",
      "status": "in_progress",
      "role": "unknown",
      "content": [
        {
          "type": "input_text",
          "text": "string",
          "prompt_cache_breakpoint": {
            "mode": "[recursive or deeply nested schema]"
          }
        }
      ],
      "phase": "commentary"
    }
  ],
  "has_more": true,
  "first_id": "string",
  "last_id": "string"
}

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