Pydantic AI (gateway)

Route OpenAI-compatible Pydantic AI model calls through the Respan gateway to use 250+ models from different providers. Only your RESPAN_API_KEY is needed — no separate provider keys required.

Setup

Install packages

$ pip install respan-ai respan-instrumentation-pydantic-ai pydantic-ai

Set environment variables

$ export RESPAN_API_KEY="YOUR_RESPAN_API_KEY"

No OPENAI_API_KEY needed — the Respan gateway handles provider authentication.

Point Pydantic AI to the Respan gateway

Python

1 import os
2 
3 respan_api_key = os.environ["RESPAN_API_KEY"]
4 respan_base_url = os.getenv("RESPAN_BASE_URL", "https://api.respan.ai/api")
5 
6 os.environ["OPENAI_API_KEY"] = respan_api_key
7 os.environ["OPENAI_BASE_URL"] = respan_base_url
8 
9 from pydantic_ai import Agent
10 
11 agent = Agent(
12     model="openai:gpt-4o",
13     system_prompt="You are a helpful assistant.",
14 )
15 
16 result = agent.run_sync("What is the capital of France?")
17 print(result.output)

Switch models

Change the model string to another OpenAI-compatible model ID to switch providers through the same gateway.

1 agent = Agent(
2     model="openai:claude-sonnet-4-5-20250929",
3     system_prompt="You are a helpful assistant.",
4 )

See the full model list.

1	import os
2
3	respan_api_key = os.environ["RESPAN_API_KEY"]
4	respan_base_url = os.getenv("RESPAN_BASE_URL", "https://api.respan.ai/api")
5
6	os.environ["OPENAI_API_KEY"] = respan_api_key
7	os.environ["OPENAI_BASE_URL"] = respan_base_url
8
9	from pydantic_ai import Agent
10
11	agent = Agent(
12	model="openai:gpt-4o",
13	system_prompt="You are a helpful assistant.",
14	)
15
16	result = agent.run_sync("What is the capital of France?")
17	print(result.output)

1	agent = Agent(
2	model="openai:claude-sonnet-4-5-20250929",
3	system_prompt="You are a helpful assistant.",
4	)