Gateway Python Library

Track Costs

Every request returns token counts and dollar costs — in headers or in code. 

# Point any SDK at the gateway — costs come back in headers
curl http://localhost:7680/v1/chat/completions \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "X-Majordomo-Key: your-key" \
  -d '{"model": "gpt-4o", "messages": [{"role": "user", "content": "Hello!"}]}'

# Response headers:
# X-Majordomo-Input-Cost:  0.000125
# X-Majordomo-Output-Cost: 0.000250
# X-Majordomo-Total-Cost:  0.000375
from majordomo_llm import get_llm_instance

llm = get_llm_instance("openai", "gpt-4o")
response = await llm.get_response("Explain async/await in Python.")

print(f"Cost: ${response.total_cost:.6f}")
print(f"Tokens: {response.input_tokens} in / {response.output_tokens} out")
Python Library

Get Structured Output

Define a Pydantic model, get typed results — one API across all providers. 

from pydantic import BaseModel
from majordomo_llm import get_llm_instance

class MovieReview(BaseModel):
    title: str
    rating: float
    summary: str

llm = get_llm_instance("anthropic", "claude-sonnet-4-20250514")
response = await llm.get_structured_json_response(
    response_model=MovieReview,
    user_prompt="Review the movie Inception.",
)

print(f"{response.content.title}: {response.content.rating}/10")
print(f"Cost: ${response.total_cost:.6f}")
Python Library

Add Automatic Failover

Cascade across providers — if one fails, the next picks up automatically. 

from majordomo_llm import LLMCascade

cascade = LLMCascade([
    ("anthropic", "claude-sonnet-4-20250514"),  # Primary
    ("openai", "gpt-4o"),                        # Fallback
    ("gemini", "gemini-2.5-flash"),              # Last resort
])

response = await cascade.get_response("Summarize this quarter's metrics.")
print(response.content)  # Whichever provider responded first
Gateway Python Library Frameworks

Route Through a Gateway

Deploy the gateway, then point any client, library, or framework at it. 

# Deploy the gateway, then point any HTTP client at it
curl http://localhost:7680/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "X-Majordomo-Key: your-key" \
  -H "X-Majordomo-App-Name: my-app" \
  -d '{"model": "claude-sonnet-4-20250514", "max_tokens": 1024,
       "messages": [{"role": "user", "content": "Hello!"}]}'
from majordomo_llm import get_llm_instance

llm = get_llm_instance(
    "anthropic", "claude-sonnet-4-20250514",
    base_url="http://localhost:7680",
    default_headers={"X-Majordomo-Key": "your-key"},
)
response = await llm.get_response("Hello!")
from pydantic_ai import Agent
from majordomo_frameworks.pydantic_ai import create_model, build_extra_headers

model = create_model("openai", "gpt-4o", gateway_url="http://localhost:7680")
agent = Agent(model)
result = await agent.run(
    "Summarize this document.",
    model_settings={"extra_headers": build_extra_headers(
        majordomo_key="your-key", app_name="my-agent",
    )},
)