POST
/
chat
/
completions
Create chat completion
curl --request POST \
  --url https://api.openai.com/v1/chat/completions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "metadata": {},
  "temperature": 1,
  "top_p": 1,
  "user": "user-1234",
  "service_tier": "auto",
  "messages": [
    {
      "content": "<string>",
      "role": "developer",
      "name": "<string>"
    }
  ],
  "model": "gpt-4o",
  "modalities": [
    "text"
  ],
  "reasoning_effort": "medium",
  "max_completion_tokens": 123,
  "frequency_penalty": 0,
  "presence_penalty": 0,
  "web_search_options": {
    "user_location": {
      "type": "approximate",
      "approximate": {
        "country": "<string>",
        "region": "<string>",
        "city": "<string>",
        "timezone": "<string>"
      }
    },
    "search_context_size": "medium"
  },
  "top_logprobs": 10,
  "response_format": {
    "type": "text"
  },
  "audio": {
    "voice": "ash",
    "format": "wav"
  },
  "store": false,
  "stream": false,
  "stop": "\n",
  "logit_bias": null,
  "logprobs": false,
  "max_tokens": 123,
  "n": 1,
  "prediction": {
    "type": "content",
    "content": "<string>"
  },
  "seed": 0,
  "stream_options": null,
  "tools": [
    {
      "type": "function",
      "function": {
        "description": "<string>",
        "name": "<string>",
        "parameters": {},
        "strict": false
      }
    }
  ],
  "tool_choice": "none",
  "parallel_tool_calls": true,
  "function_call": "none",
  "functions": [
    {
      "description": "<string>",
      "name": "<string>",
      "parameters": {}
    }
  ]
}'
{
  "id": "<string>",
  "choices": [
    {
      "finish_reason": "stop",
      "index": 123,
      "message": {
        "content": "<string>",
        "refusal": "<string>",
        "tool_calls": [
          {
            "id": "<string>",
            "type": "function",
            "function": {
              "name": "<string>",
              "arguments": "<string>"
            }
          }
        ],
        "annotations": [
          {
            "type": "url_citation",
            "url_citation": {
              "end_index": 123,
              "start_index": 123,
              "url": "<string>",
              "title": "<string>"
            }
          }
        ],
        "role": "assistant",
        "function_call": {
          "arguments": "<string>",
          "name": "<string>"
        },
        "audio": {
          "id": "<string>",
          "expires_at": 123,
          "data": "<string>",
          "transcript": "<string>"
        }
      },
      "logprobs": {
        "content": [
          {
            "token": "<string>",
            "logprob": 123,
            "bytes": [
              123
            ],
            "top_logprobs": [
              {
                "token": "<string>",
                "logprob": 123,
                "bytes": [
                  "<any>"
                ]
              }
            ]
          }
        ],
        "refusal": [
          {
            "token": "<string>",
            "logprob": 123,
            "bytes": [
              123
            ],
            "top_logprobs": [
              {
                "token": "<string>",
                "logprob": 123,
                "bytes": [
                  "<any>"
                ]
              }
            ]
          }
        ]
      }
    }
  ],
  "created": 123,
  "model": "<string>",
  "service_tier": "auto",
  "system_fingerprint": "<string>",
  "object": "chat.completion",
  "usage": {
    "completion_tokens": 0,
    "prompt_tokens": 0,
    "total_tokens": 0,
    "completion_tokens_details": {
      "accepted_prediction_tokens": 0,
      "audio_tokens": 0,
      "reasoning_tokens": 0,
      "rejected_prediction_tokens": 0
    },
    "prompt_tokens_details": {
      "audio_tokens": 0,
      "cached_tokens": 0
    }
  }
}

Authorizations

​
Authorization
string
header
required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Body

application/json
​
messages
(Developer message · object | System message · object | User message · object | Assistant message · object | Tool message · object | Function message · object)[]
required

A list of messages comprising the conversation so far. Depending on the model you use, different message types (modalities) are supported, like text, images, and audio.

Minimum length: 1
​
model
required

Model ID used to generate the response, like gpt-4o or o3. OpenAI offers a wide range of models with different capabilities, performance characteristics, and price points. Refer to the model guide to browse and compare available models.

Example:

"gpt-4o"

​
modalities
enum<string>[] | null

Output types that you would like the model to generate. Most models are capable of generating text, which is the default:

["text"]

The gpt-4o-audio-preview model can also be used to generate audio. To request that this model generate both text and audio responses, you can use:

["text", "audio"]

​
reasoning_effort
enum<string> | null
default:medium

o-series models only

Constrains effort on reasoning for reasoning models. Currently supported values are low, medium, and high. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response.

Available options:
low,
medium,
high
​
max_completion_tokens
integer | null

An upper bound for the number of tokens that can be generated for a completion, including visible output tokens and reasoning tokens.

​
frequency_penalty
number | null
default:0

Number between -2.0 and 2.0. Positive values penalize new tokens based on their existing frequency in the text so far, decreasing the model's likelihood to repeat the same line verbatim.

Required range: -2 <= x <= 2
​
presence_penalty
number | null
default:0

Number between -2.0 and 2.0. Positive values penalize new tokens based on whether they appear in the text so far, increasing the model's likelihood to talk about new topics.

Required range: -2 <= x <= 2
​
web_search_options
object

This tool searches the web for relevant results to use in a response. Learn more about the web search tool.

​
top_logprobs
integer | null

An integer between 0 and 20 specifying the number of most likely tokens to return at each token position, each with an associated log probability. logprobs must be set to true if this parameter is used.

Required range: 0 <= x <= 20
​
response_format
object

An object specifying the format that the model must output.

Setting to { "type": "json_schema", "json_schema": {...} } enables Structured Outputs which ensures the model will match your supplied JSON schema. Learn more in the Structured Outputs guide.

Setting to { "type": "json_object" } enables the older JSON mode, which ensures the message the model generates is valid JSON. Using json_schema is preferred for models that support it.

Default response format. Used to generate text responses.

​
audio
object | null

Parameters for audio output. Required when audio output is requested with modalities: ["audio"]. Learn more.

​
store
boolean | null
default:false

Whether or not to store the output of this chat completion request for use in our model distillation or evals products.

​
stream
boolean | null
default:false

If set to true, the model response data will be streamed to the client as it is generated using server-sent events. See the Streaming section below for more information, along with the streaming responses guide for more information on how to handle the streaming events.

​
stop
default:<|endoftext|>

Up to 4 sequences where the API will stop generating further tokens. The returned text will not contain the stop sequence.

Example:

"\n"

​
logit_bias
object | null

Modify the likelihood of specified tokens appearing in the completion.

Accepts a JSON object that maps tokens (specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically, the bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model, but values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should result in a ban or exclusive selection of the relevant token.

​
logprobs
boolean | null
default:false

Whether to return log probabilities of the output tokens or not. If true, returns the log probabilities of each output token returned in the content of message.

​
max_tokens
integer | null
deprecated

The maximum number of tokens that can be generated in the chat completion. This value can be used to control costs for text generated via API.

This value is now deprecated in favor of max_completion_tokens, and is not compatible with o-series models.

​
n
integer | null
default:1

How many chat completion choices to generate for each input message. Note that you will be charged based on the number of generated tokens across all of the choices. Keep n as 1 to minimize costs.

Required range: 1 <= x <= 128
Example:

1

​
prediction
object

Configuration for a Predicted Output, which can greatly improve response times when large parts of the model response are known ahead of time. This is most common when you are regenerating a file with only minor changes to most of the content.

Static predicted output content, such as the content of a text file that is being regenerated.

​
seed
integer | null

This feature is in Beta. If specified, our system will make a best effort to sample deterministically, such that repeated requests with the same seed and parameters should return the same result. Determinism is not guaranteed, and you should refer to the system_fingerprint response parameter to monitor changes in the backend.

Required range: -9223372036854776000 <= x <= 9223372036854776000
​
stream_options
object | null

Options for streaming response. Only set this when you set stream: true.

​
tools
object[]

A list of tools the model may call. Currently, only functions are supported as a tool. Use this to provide a list of functions the model may generate JSON inputs for. A max of 128 functions are supported.

​
tool_choice

Controls which (if any) tool is called by the model. none means the model will not call any tool and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools. Specifying a particular tool via {"type": "function", "function": {"name": "my_function"}} forces the model to call that tool.

none is the default when no tools are present. auto is the default if tools are present.

none means the model will not call any tool and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools.

Available options:
none,
auto,
required
​
parallel_tool_calls
boolean
default:true

Whether to enable parallel function calling during tool use.

​
function_call
deprecated

Deprecated in favor of tool_choice.

Controls which (if any) function is called by the model.

none means the model will not call a function and instead generates a message.

auto means the model can pick between generating a message or calling a function.

Specifying a particular function via {"name": "my_function"} forces the model to call that function.

none is the default when no functions are present. auto is the default if functions are present.

none means the model will not call a function and instead generates a message. auto means the model can pick between generating a message or calling a function.

Available options:
none,
auto
​
functions
object[]
deprecated

Deprecated in favor of tools.

A list of functions the model may generate JSON inputs for.

Required array length: 1 - 128 elements
​
metadata
object | null

Set of 16 key-value pairs that can be attached to an object. This can be useful for storing additional information about the object in a structured format, and querying for objects via API or the dashboard.

Keys are strings with a maximum length of 64 characters. Values are strings with a maximum length of 512 characters.

​
temperature
number | null
default:1

What sampling temperature to use, between 0 and 2. Higher values like 0.8 will make the output more random, while lower values like 0.2 will make it more focused and deterministic. We generally recommend altering this or top_p but not both.

Required range: 0 <= x <= 2
Example:

1

​
top_p
number | null
default:1

An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered.

We generally recommend altering this or temperature but not both.

Required range: 0 <= x <= 1
Example:

1

​
user
string

A unique identifier representing your end-user, which can help OpenAI to monitor and detect abuse. Learn more.

Example:

"user-1234"

​
service_tier
enum<string> | null
default:auto

Specifies the latency tier to use for processing the request. This parameter is relevant for customers subscribed to the scale tier service:

  • If set to 'auto', and the Project is Scale tier enabled, the system will utilize scale tier credits until they are exhausted.
  • If set to 'auto', and the Project is not Scale tier enabled, the request will be processed using the default service tier with a lower uptime SLA and no latency guarentee.
  • If set to 'default', the request will be processed using the default service tier with a lower uptime SLA and no latency guarentee.
  • If set to 'economy', the request will be processed with the Economy service tier at the specified price. Economy requests have longer response times and may experience Resource Unavailable errors. See the docs for more information.
  • When not set, the default behavior is 'auto'.

When this parameter is set, the response body will include the service_tier utilized.

Available options:
auto,
default,
economy

Response

OK

Represents a chat completion response returned by model, based on the provided input.

​
id
string
required

A unique identifier for the chat completion.

​
choices
object[]
required

A list of chat completion choices. Can be more than one if n is greater than 1.

​
created
integer
required

The Unix timestamp (in seconds) of when the chat completion was created.

​
model
string
required

The model used for the chat completion.

​
object
enum<string>
required

The object type, which is always chat.completion.

Available options:
chat.completion
​
service_tier
enum<string> | null
default:auto

Specifies the latency tier to use for processing the request. This parameter is relevant for customers subscribed to the scale tier service:

  • If set to 'auto', and the Project is Scale tier enabled, the system will utilize scale tier credits until they are exhausted.
  • If set to 'auto', and the Project is not Scale tier enabled, the request will be processed using the default service tier with a lower uptime SLA and no latency guarentee.
  • If set to 'default', the request will be processed using the default service tier with a lower uptime SLA and no latency guarentee.
  • If set to 'economy', the request will be processed with the Economy service tier at the specified price. Economy requests have longer response times and may experience Resource Unavailable errors. See the docs for more information.
  • When not set, the default behavior is 'auto'.

When this parameter is set, the response body will include the service_tier utilized.

Available options:
auto,
default,
economy
​
system_fingerprint
string

This fingerprint represents the backend configuration that the model runs with.

Can be used in conjunction with the seed request parameter to understand when backend changes have been made that might impact determinism.

​
usage
object

Usage statistics for the completion request.