# ResponseFormat

An object specifying the format that the model must output. Compatible with [GPT-4 Turbo](/docs/models/gpt-4-and-gpt-4-turbo) and all GPT-3.5 Turbo models newer than `gpt-3.5-turbo-1106`.

Setting to `{ "type": "json_object" }` enables JSON mode, which guarantees the message the model generates is valid JSON.

**Important:** when using JSON mode, you **must** also instruct the model to produce JSON yourself via a system or user message. Without this, the model may generate an unending stream of whitespace until the generation reaches the token limit, resulting in a long-running and seemingly "stuck" request. Also note that the message content may be partially cut off if `finish_reason="length"`, which indicates the generation exceeded `max_tokens` or the conversation exceeded the max context length.



## Fields

| Field                                                                                                     | Type                                                                                                      | Required                                                                                                  | Description                                                                                               | Example                                                                                                   |
| --------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------- |
| `Type`                                                                                                    | [*components.CreateChatCompletionRequestType](../../models/components/createchatcompletionrequesttype.md) | :heavy_minus_sign:                                                                                        | Must be one of `text` or `json_object`.                                                                   | json_object                                                                                               |