o3-pro

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This documentation is valid for the following list of our models:

  • openai/o3-pro

Model Overview

Designed for deeper reasoning and tougher questions, o3-pro uses more compute to deliver higher-quality answers. It’s only available in the /responses API, which supports multi-turn model interactions and will enable more advanced features in the future. Some complex requests may take a few minutes.

How to Make a Call

chevron-rightStep-by-Step Instructionshashtag

1️ Setup You Can’t Skip

▪️ Create an Accountarrow-up-right: Visit the AI/ML API website and create an account (if you don’t have one yet). ▪️ Generate an API Keyarrow-up-right: After logging in, navigate to your account dashboard and generate your API key. Ensure that key is enabled on UI.

2️ Copy the code example

At the bottom of this page, you'll find a code example that shows how to structure the request. Choose the code snippet in your preferred programming language and copy it into your development environment.

3️ Modify the code example

▪️ Replace <YOUR_AIMLAPI_KEY> with your actual AI/ML API key from your account. ▪️ Insert your question or request into the input field—this is what the model will respond to.

4️ (Optional) Adjust other optional parameters if needed

Only model and input are required parameters for this model (and we’ve already filled them in for you in the example), but you can include optional parameters if needed to adjust the model’s behavior. Below, you can find the corresponding API schema, which lists all available parameters along with notes on how to use them.

5️ Run your modified code

Run your modified code in your development environment. Response time depends on various factors, but for simple prompts it rarely exceeds a few seconds.

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API Schema

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chevron-rightChat Completions vs. Responses APIhashtag

Chat Completions The chat completions API is the older, chat-oriented interface where you send a list of messages (role: user, role: assistant, etc.), and the model returns a single response. It was designed specifically for conversational workflows and follows a structured chat message format. It is now considered a legacy interface.

Responses The Responses API is the newer, unified interface used across OpenAI’s latest models. Instead of focusing only on chat, it supports multiple input types (text, images, audio, tools, etc.) and multiple output modalities (text, JSON, images, audio, video). It is more flexible, more consistent across models, and intended to replace chat completions entirely.

This endpoint is currently used only with OpenAI models. Some models support both the /chat/completions and /responses endpoints, while others (like openai/o3-pro) support only one of them.

post
Body
modelstring · enumRequiredPossible values:
inputany ofRequired

Text, image, or file inputs to the model, used to generate a response.

stringOptional

A text input to the model, equivalent to a text input with the user role.

or
or
or
or
or
or
or
or
or
or
or
or
backgroundbooleanOptional

Whether to run the model response in the background.

Default: false
instructionsstring · nullableOptional

A system (or developer) message inserted into the model's context.

When using along with previous_response_id, the instructions from a previous response will not be carried over to the next response. This makes it simple to swap out system (or developer) messages in new responses.

max_output_tokensintegerOptional

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

previous_response_idstring · nullableOptional

The unique ID of the previous response to the model. Use this to create multi-turn conversations.

storeboolean · nullableOptional

Whether to store the generated model response for later retrieval via API.

Default: false
streamboolean · nullableOptional

If set to true, the model response data will be streamed to the client as it is generated using server-sent events.

Default: false
truncationstring · enumOptional

The truncation strategy to use for the model response.

  • auto: If the context of this response and previous ones exceeds the model's context window size, the model will truncate the response to fit the context window by dropping input items in the middle of the conversation.
  • disabled (default): If a model response will exceed the context window size for a model, the request will fail with a 400 error.
Default: disabledPossible values:
tool_choiceany ofOptional

How the model should select which tool (or tools) to use when generating a response.

string · enumOptional

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.

Possible values:
or
or
Responses
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200Success
backgroundboolean · nullableOptional

Whether to run the model response in the background.

Example: false
created_atnumberRequired

Unix timestamp (in seconds) of when this Response was created.

Example: 1762343744
idstringRequired

Unique identifier for this Response.

Example: resp_68963fb142d08197b4d3ae3ad852542c054845c6ea84caa2
instructionsany ofOptional

A system (or developer) message inserted into the model's context.

stringOptional

A text input to the model, equivalent to a text input with the developer role.

or
or
any · nullableOptional
max_output_tokensinteger · nullableOptional

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

modelstringRequired

Model ID used to generate the response.

Example: openai/o3-pro
objectstring · enumRequired

The object type of this resource - always set to response.

Example: responsePossible values:
output_textstring · nullableOptional

SDK-only convenience property that contains the aggregated text output from all output_text items in the output array, if any are present. Supported in the Python and JavaScript SDKs.

Example: Hi! How’s your day going?
parallel_tool_callsbooleanRequired

Whether to allow the model to run tool calls in parallel.

Example: false
previous_response_idstring · nullableOptional

The unique ID of the previous response to the model. Use this to create multi-turn conversations.

service_tierstring · nullableOptional

Specifies the processing type used for serving the request.

statusstring · enumOptional

The status of the response generation.

Example: completedPossible values:
temperaturenumber · max: 2 · nullableOptional

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.

tool_choiceany ofOptional

How the model should select which tool (or tools) to use when generating a response.

string · enumOptional

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.

Possible values:
or
or
or
any · nullableOptional
top_pnumber · nullableOptional

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.

truncationstring · enum · nullableOptional

The truncation strategy to use for the model response.

  • auto: If the context of this response and previous ones exceeds the model's context window size, the model will truncate the response to fit the context window by dropping input items in the middle of the conversation.
  • disabled (default): If a model response will exceed the context window size for a model, the request will fail with a 400 error.
Possible values:
post
/v1/responses
200Success

Code Example

chevron-rightResponsehashtag

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