Pydantic AI (gateway)

Route Pydantic AI model calls through the Respan gateway to use 1000+ models from different providers. Only your RESPAN_API_KEY is needed.

Setup

pip install pydantic-ai python-dotenv

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

import os
from pydantic_ai import Agent
respan_api_key = os.environ["RESPAN_API_KEY"]
respan_base_url = os.getenv("RESPAN_BASE_URL", "https://api.respan.ai/api").rstrip("/")
gateway_api_key = os.getenv("RESPAN_GATEWAY_API_KEY", respan_api_key)
model = os.getenv("RESPAN_MODEL", "gpt-4o")
os.environ["OPENAI_BASE_URL"] = os.getenv("RESPAN_GATEWAY_BASE_URL", respan_base_url).rstrip("/")
os.environ["OPENAI_API_KEY"] = gateway_api_key
agent = Agent(
    model=f"openai:{model}",
    system_prompt="You are a helpful assistant.",
)
result = agent.run_sync("What is the capital of France?")
print(result.output)

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.

import os
from pydantic_ai import Agent
respan_api_key = os.environ["RESPAN_API_KEY"]
respan_base_url = os.getenv("RESPAN_BASE_URL", "https://api.respan.ai/api").rstrip("/")
model = os.getenv("ANTHROPIC_MODEL", "claude-sonnet-4-5-20250929")
os.environ["ANTHROPIC_BASE_URL"] = f"{respan_base_url}/anthropic"
os.environ["ANTHROPIC_API_KEY"] = respan_api_key
agent = Agent(
    model=f"anthropic:{model}",
    system_prompt="You are a helpful assistant.",
)

Switch models

Change the model string or RESPAN_MODEL value to another gateway model ID. The openai: prefix uses the Responses API, which serves OpenAI models only. Use the openai-chat: prefix for Claude, Gemini, and other providers so Pydantic AI calls Chat Completions.

agent = Agent(
    model="openai-chat:gemini/gemini-3.5-flash",
    system_prompt="You are a helpful assistant.",
)

See the full model list.