Pydantic AI (gateway)

Route Pydantic AI model calls through the Respan gateway to use 250+ models from different providers. Only your RESPAN_API_KEY is needed.

Setup

Install packages

$ pip install pydantic-ai python-dotenv

Set environment variables

$ export RESPAN_API_KEY="YOUR_RESPAN_API_KEY"
$ # Optional overrides
$ export RESPAN_BASE_URL="https://api.respan.ai/api"
$ export RESPAN_MODEL="gpt-4o"

No provider API key is needed in the application runtime. The Respan gateway handles provider authentication.

Point Pydantic AI to the Respan gateway

Python

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

Pydantic AI reads OpenAI-compatible settings from OpenAI-shaped environment variables for this provider. The code maps those variables from RESPAN_API_KEY; users do not need an OpenAI provider key.

Anthropic provider

If you use Pydantic AI’s Anthropic provider, point it at the Anthropic-compatible Respan gateway route and keep using the Respan key as the runtime secret.

Python

1 import os
2 
3 from pydantic_ai import Agent
4 
5 respan_api_key = os.environ["RESPAN_API_KEY"]
6 respan_base_url = os.getenv("RESPAN_BASE_URL", "https://api.respan.ai/api").rstrip("/")
7 model = os.getenv("ANTHROPIC_MODEL", "claude-sonnet-4-5-20250929")
8 
9 os.environ["ANTHROPIC_BASE_URL"] = f"{respan_base_url}/anthropic"
10 os.environ["ANTHROPIC_API_KEY"] = respan_api_key
11 
12 agent = Agent(
13     model=f"anthropic:{model}",
14     system_prompt="You are a helpful assistant.",
15 )

Switch models

Change the model string or RESPAN_MODEL value to another gateway model ID.

1 agent = Agent(
2     model="openai:gemini/gemini-2.5-flash",
3     system_prompt="You are a helpful assistant.",
4 )

See the full model list.