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OpenAI

Install

To use OpenAI models or OpenAI-compatible APIs, you need to either install pydantic-ai, or install pydantic-ai-slim with the openai optional group:

pip install "pydantic-ai-slim[openai]"

uv add "pydantic-ai-slim[openai]"

Configuration

To use OpenAIChatModel with the OpenAI API, go to platform.openai.com and follow your nose until you find the place to generate an API key.

Environment variable

Once you have the API key, you can set it as an environment variable:

export OPENAI_API_KEY='your-api-key'

You can then use OpenAIChatModel by name:

from pydantic_ai import Agent

agent = Agent('openai:gpt-5')
...

Or initialise the model directly with just the model name:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel

model = OpenAIChatModel('gpt-5')
agent = Agent(model)
...

By default, the OpenAIChatModel uses the OpenAIProvider with the base_url set to https://api.openai.com/v1.

Configure the provider

If you want to pass parameters in code to the provider, you can programmatically instantiate the OpenAIProvider and pass it to the model:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openai import OpenAIProvider

model = OpenAIChatModel('gpt-5', provider=OpenAIProvider(api_key='your-api-key'))
agent = Agent(model)
...

Custom OpenAI Client

OpenAIProvider also accepts a custom AsyncOpenAI client via the openai_client parameter, so you can customise the organization, project, base_url etc. as defined in the OpenAI API docs.

custom_openai_client.py
from openai import AsyncOpenAI

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openai import OpenAIProvider

client = AsyncOpenAI(max_retries=3)
model = OpenAIChatModel('gpt-5', provider=OpenAIProvider(openai_client=client))
agent = Agent(model)
...

You could also use the AsyncAzureOpenAI client to use the Azure OpenAI API. Note that the AsyncAzureOpenAI is a subclass of AsyncOpenAI.

from openai import AsyncAzureOpenAI

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openai import OpenAIProvider

client = AsyncAzureOpenAI(
    azure_endpoint='...',
    api_version='2024-07-01-preview',
    api_key='your-api-key',
)

model = OpenAIChatModel(
    'gpt-5',
    provider=OpenAIProvider(openai_client=client),
)
agent = Agent(model)
...

OpenAI Responses API

Pydantic AI also supports OpenAI's Responses API through the

You can use OpenAIResponsesModel by name:

from pydantic_ai import Agent

agent = Agent('openai-responses:gpt-5')
...

Or initialise the model directly with just the model name:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIResponsesModel

model = OpenAIResponsesModel('gpt-5')
agent = Agent(model)
...

You can learn more about the differences between the Responses API and Chat Completions API in the OpenAI API docs.

Built-in tools

The Responses API has built-in tools that you can use instead of building your own:

  • Web search: allow models to search the web for the latest information before generating a response.
  • Code interpreter: allow models to write and run Python code in a sandboxed environment before generating a response.
  • Image generation: allow models to generate images based on a text prompt.
  • File search: allow models to search your files for relevant information before generating a response.
  • Computer use: allow models to use a computer to perform tasks on your behalf.

Web search, Code interpreter, and Image generation are natively supported through the Built-in tools feature.

File search and Computer use can be enabled by passing an openai.types.responses.FileSearchToolParam or openai.types.responses.ComputerToolParam in the openai_builtin_tools setting on OpenAIResponsesModelSettings. They don't currently generate BuiltinToolCallPart or BuiltinToolReturnPart parts in the message history, or streamed events; please submit an issue if you need native support for these built-in tools.

file_search_tool.py
from openai.types.responses import FileSearchToolParam

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIResponsesModel, OpenAIResponsesModelSettings

model_settings = OpenAIResponsesModelSettings(
    openai_builtin_tools=[
        FileSearchToolParam(
            type='file_search',
            vector_store_ids=['your-history-book-vector-store-id']
        )
    ],
)
model = OpenAIResponsesModel('gpt-5')
agent = Agent(model=model, model_settings=model_settings)

result = agent.run_sync('Who was Albert Einstein?')
print(result.output)
#> Albert Einstein was a German-born theoretical physicist.

Referencing earlier responses

The Responses API supports referencing earlier model responses in a new request using a previous_response_id parameter, to ensure the full conversation state including reasoning items are kept in context. This is available through the openai_previous_response_id field in OpenAIResponsesModelSettings.

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIResponsesModel, OpenAIResponsesModelSettings

model = OpenAIResponsesModel('gpt-5')
agent = Agent(model=model)

result = agent.run_sync('The secret is 1234')
model_settings = OpenAIResponsesModelSettings(
    openai_previous_response_id=result.all_messages()[-1].provider_response_id
)
result = agent.run_sync('What is the secret code?', model_settings=model_settings)
print(result.output)
#> 1234

By passing the provider_response_id from an earlier run, you can allow the model to build on its own prior reasoning without needing to resend the full message history.

Automatically referencing earlier responses

When the openai_previous_response_id field is set to 'auto', Pydantic AI will automatically select the most recent provider_response_id from message history and omit messages that came before it, letting the OpenAI API leverage server-side history instead for improved efficiency.

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIResponsesModel, OpenAIResponsesModelSettings

model = OpenAIResponsesModel('gpt-5')
agent = Agent(model=model)

result1 = agent.run_sync('Tell me a joke.')
print(result1.output)
#> Did you hear about the toothpaste scandal? They called it Colgate.

# When set to 'auto', the most recent provider_response_id
# and messages after it are sent as request.
model_settings = OpenAIResponsesModelSettings(openai_previous_response_id='auto')
result2 = agent.run_sync(
    'Explain?',
    message_history=result1.new_messages(),
    model_settings=model_settings
)
print(result2.output)
#> This is an excellent joke invented by Samuel Colvin, it needs no explanation.

OpenAI-compatible Models

Many providers and models are compatible with the OpenAI API, and can be used with OpenAIChatModel in Pydantic AI. Before getting started, check the installation and configuration instructions above.

To use another OpenAI-compatible API, you can make use of the base_url and api_key arguments from OpenAIProvider:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openai import OpenAIProvider

model = OpenAIChatModel(
    'model_name',
    provider=OpenAIProvider(
        base_url='https://<openai-compatible-api-endpoint>', api_key='your-api-key'
    ),
)
agent = Agent(model)
...

Various providers also have their own provider classes so that you don't need to specify the base URL yourself and you can use the standard <PROVIDER>_API_KEY environment variable to set the API key. When a provider has its own provider class, you can use the Agent("<provider>:<model>") shorthand, e.g. Agent("deepseek:deepseek-chat") or Agent("openrouter:google/gemini-2.5-pro-preview"), instead of building the OpenAIChatModel explicitly. Similarly, you can pass the provider name as a string to the provider argument on OpenAIChatModel instead of building instantiating the provider class explicitly.

Model Profile

Sometimes, the provider or model you're using will have slightly different requirements than OpenAI's API or models, like having different restrictions on JSON schemas for tool definitions, or not supporting tool definitions to be marked as strict.

When using an alternative provider class provided by Pydantic AI, an appropriate model profile is typically selected automatically based on the model name. If the model you're using is not working correctly out of the box, you can tweak various aspects of how model requests are constructed by providing your own ModelProfile (for behaviors shared among all model classes) or OpenAIModelProfile (for behaviors specific to OpenAIChatModel):

from pydantic_ai import Agent, InlineDefsJsonSchemaTransformer
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.profiles.openai import OpenAIModelProfile
from pydantic_ai.providers.openai import OpenAIProvider

model = OpenAIChatModel(
    'model_name',
    provider=OpenAIProvider(
        base_url='https://<openai-compatible-api-endpoint>.com', api_key='your-api-key'
    ),
    profile=OpenAIModelProfile(
        json_schema_transformer=InlineDefsJsonSchemaTransformer,  # Supported by any model class on a plain ModelProfile
        openai_supports_strict_tool_definition=False  # Supported by OpenAIModel only, requires OpenAIModelProfile
    )
)
agent = Agent(model)

DeepSeek

To use the DeepSeek provider, first create an API key by following the Quick Start guide.

You can then set the DEEPSEEK_API_KEY environment variable and use DeepSeekProvider by name:

from pydantic_ai import Agent

agent = Agent('deepseek:deepseek-chat')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.deepseek import DeepSeekProvider

model = OpenAIChatModel(
    'deepseek-chat',
    provider=DeepSeekProvider(api_key='your-deepseek-api-key'),
)
agent = Agent(model)
...

You can also customize any provider with a custom http_client:

from httpx import AsyncClient

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.deepseek import DeepSeekProvider

custom_http_client = AsyncClient(timeout=30)
model = OpenAIChatModel(
    'deepseek-chat',
    provider=DeepSeekProvider(
        api_key='your-deepseek-api-key', http_client=custom_http_client
    ),
)
agent = Agent(model)
...

Ollama

Pydantic AI supports both self-hosted Ollama servers (running locally or remotely) and Ollama Cloud.

For servers running locally, use the http://localhost:11434/v1 base URL. For Ollama Cloud, use https://ollama.com/v1 and ensure an API key is set.

You can set the OLLAMA_BASE_URL and (optionally) OLLAMA_API_KEY environment variables and use OllamaProvider by name:

from pydantic_ai import Agent

agent = Agent('ollama:gpt-oss:20b')
...

Or initialise the model and provider directly:

from pydantic import BaseModel

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.ollama import OllamaProvider


class CityLocation(BaseModel):
    city: str
    country: str


ollama_model = OpenAIChatModel(
    model_name='gpt-oss:20b',
    provider=OllamaProvider(base_url='http://localhost:11434/v1'),  # (1)!
)
agent = Agent(ollama_model, output_type=CityLocation)

result = agent.run_sync('Where were the olympics held in 2012?')
print(result.output)
#> city='London' country='United Kingdom'
print(result.usage())
#> RunUsage(input_tokens=57, output_tokens=8, requests=1)
  1. For Ollama Cloud, use the base_url='https://ollama.com/v1' and set the OLLAMA_API_KEY environment variable.

Azure AI Foundry

To use Azure AI Foundry as your provider, you can set the AZURE_OPENAI_ENDPOINT, AZURE_OPENAI_API_KEY, and OPENAI_API_VERSION environment variables and use AzureProvider by name:

from pydantic_ai import Agent

agent = Agent('azure:gpt-5')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.azure import AzureProvider

model = OpenAIChatModel(
    'gpt-5',
    provider=AzureProvider(
        azure_endpoint='your-azure-endpoint',
        api_version='your-api-version',
        api_key='your-api-key',
    ),
)
agent = Agent(model)
...

OpenRouter

To use OpenRouter, first create an API key at openrouter.ai/keys.

You can set the OPENROUTER_API_KEY environment variable and use OpenRouterProvider by name:

from pydantic_ai import Agent

agent = Agent('openrouter:anthropic/claude-3.5-sonnet')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openrouter import OpenRouterProvider

model = OpenAIChatModel(
    'anthropic/claude-3.5-sonnet',
    provider=OpenRouterProvider(api_key='your-openrouter-api-key'),
)
agent = Agent(model)
...

Vercel AI Gateway

To use Vercel's AI Gateway, first follow the documentation instructions on obtaining an API key or OIDC token.

You can set the VERCEL_AI_GATEWAY_API_KEY and VERCEL_OIDC_TOKEN environment variables and use VercelProvider by name:

from pydantic_ai import Agent

agent = Agent('vercel:anthropic/claude-4-sonnet')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.vercel import VercelProvider

model = OpenAIChatModel(
    'anthropic/claude-4-sonnet',
    provider=VercelProvider(api_key='your-vercel-ai-gateway-api-key'),
)
agent = Agent(model)
...

Grok (xAI)

Go to xAI API Console and create an API key.

You can set the GROK_API_KEY environment variable and use GrokProvider by name:

from pydantic_ai import Agent

agent = Agent('grok:grok-2-1212')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.grok import GrokProvider

model = OpenAIChatModel(
    'grok-2-1212',
    provider=GrokProvider(api_key='your-xai-api-key'),
)
agent = Agent(model)
...

MoonshotAI

Create an API key in the Moonshot Console.

You can set the MOONSHOTAI_API_KEY environment variable and use MoonshotAIProvider by name:

from pydantic_ai import Agent

agent = Agent('moonshotai:kimi-k2-0711-preview')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.moonshotai import MoonshotAIProvider

model = OpenAIChatModel(
    'kimi-k2-0711-preview',
    provider=MoonshotAIProvider(api_key='your-moonshot-api-key'),
)
agent = Agent(model)
...

GitHub Models

To use GitHub Models, you'll need a GitHub personal access token with the models: read permission.

You can set the GITHUB_API_KEY environment variable and use GitHubProvider by name:

from pydantic_ai import Agent

agent = Agent('github:xai/grok-3-mini')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.github import GitHubProvider

model = OpenAIChatModel(
    'xai/grok-3-mini',  # GitHub Models uses prefixed model names
    provider=GitHubProvider(api_key='your-github-token'),
)
agent = Agent(model)
...

GitHub Models supports various model families with different prefixes. You can see the full list on the GitHub Marketplace or the public catalog endpoint.

Perplexity

Follow the Perplexity getting started guide to create an API key.

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.openai import OpenAIProvider

model = OpenAIChatModel(
    'sonar-pro',
    provider=OpenAIProvider(
        base_url='https://api.perplexity.ai',
        api_key='your-perplexity-api-key',
    ),
)
agent = Agent(model)
...

Fireworks AI

Go to Fireworks.AI and create an API key in your account settings.

You can set the FIREWORKS_API_KEY environment variable and use FireworksProvider by name:

from pydantic_ai import Agent

agent = Agent('fireworks:accounts/fireworks/models/qwq-32b')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.fireworks import FireworksProvider

model = OpenAIChatModel(
    'accounts/fireworks/models/qwq-32b',  # model library available at https://fireworks.ai/models
    provider=FireworksProvider(api_key='your-fireworks-api-key'),
)
agent = Agent(model)
...

Together AI

Go to Together.ai and create an API key in your account settings.

You can set the TOGETHER_API_KEY environment variable and use TogetherProvider by name:

from pydantic_ai import Agent

agent = Agent('together:meta-llama/Llama-3.3-70B-Instruct-Turbo-Free')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.together import TogetherProvider

model = OpenAIChatModel(
    'meta-llama/Llama-3.3-70B-Instruct-Turbo-Free',  # model library available at https://www.together.ai/models
    provider=TogetherProvider(api_key='your-together-api-key'),
)
agent = Agent(model)
...

Heroku AI

To use Heroku AI, first create an API key.

You can set the HEROKU_INFERENCE_KEY and (optionally )HEROKU_INFERENCE_URL environment variables and use HerokuProvider by name:

from pydantic_ai import Agent

agent = Agent('heroku:claude-3-7-sonnet')
...

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.heroku import HerokuProvider

model = OpenAIChatModel(
    'claude-3-7-sonnet',
    provider=HerokuProvider(api_key='your-heroku-inference-key'),
)
agent = Agent(model)
...

Cerebras

To use Cerebras, you need to create an API key in the Cerebras Console.

You can set the CEREBRAS_API_KEY environment variable and use CerebrasProvider by name:

from pydantic_ai import Agent

agent = Agent('cerebras:llama3.3-70b')
result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.cerebras import CerebrasProvider

model = OpenAIChatModel(
    'llama3.3-70b',
    provider=CerebrasProvider(api_key='your-cerebras-api-key'),
)
agent = Agent(model)

result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.

LiteLLM

To use LiteLLM, set the configs as outlined in the doc. In LiteLLMProvider, you can pass api_base and api_key. The value of these configs will depend on your setup. For example, if you are using OpenAI models, then you need to pass https://api.openai.com/v1 as the api_base and your OpenAI API key as the api_key. If you are using a LiteLLM proxy server running on your local machine, then you need to pass http://localhost:<port> as the api_base and your LiteLLM API key (or a placeholder) as the api_key.

To use custom LLMs, use custom/ prefix in the model name.

Once you have the configs, use the LiteLLMProvider as follows:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.litellm import LiteLLMProvider

model = OpenAIChatModel(
    'openai/gpt-3.5-turbo',
    provider=LiteLLMProvider(
        api_base='<api-base-url>',
        api_key='<api-key>'
    )
)
agent = Agent(model)

result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.
...

Nebius AI Studio

Go to Nebius AI Studio and create an API key.

You can set the NEBIUS_API_KEY environment variable and use NebiusProvider by name:

from pydantic_ai import Agent

agent = Agent('nebius:Qwen/Qwen3-32B-fast')
result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.

Or initialise the model and provider directly:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.nebius import NebiusProvider

model = OpenAIChatModel(
    'Qwen/Qwen3-32B-fast',
    provider=NebiusProvider(api_key='your-nebius-api-key'),
)
agent = Agent(model)
result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.

OVHcloud AI Endpoints

To use OVHcloud AI Endpoints, you need to create a new API key. To do so, go to the OVHcloud manager, then in Public Cloud > AI Endpoints > API keys. Click on Create a new API key and copy your new key.

You can explore the catalog to find which models are available.

You can set the OVHCLOUD_API_KEY environment variable and use OVHcloudProvider by name:

from pydantic_ai import Agent

agent = Agent('ovhcloud:gpt-oss-120b')
result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.

If you need to configure the provider, you can use the OVHcloudProvider class:

from pydantic_ai import Agent
from pydantic_ai.models.openai import OpenAIChatModel
from pydantic_ai.providers.ovhcloud import OVHcloudProvider

model = OpenAIChatModel(
    'gpt-oss-120b',
    provider=OVHcloudProvider(api_key='your-api-key'),
)
agent = Agent(model)
result = agent.run_sync('What is the capital of France?')
print(result.output)
#> The capital of France is Paris.