fastucp-python 0.1.2

FastAPI based implementation of Universal Commerce Protocol

FastUCP ⚡️

The "FastAPI" for the Universal Commerce Protocol (UCP).

FastUCP is a high-performance, developer-friendly Python framework for building UCP-compliant Merchant Servers and Commerce Agents. It combines the strict compliance of Google's Official UCP SDK models with the intuitive developer experience of FastAPI.

🌟 Why FastUCP?

The Universal Commerce Protocol involves complex JSON schemas, rigorous validation rules, and deep object nesting. FastUCP abstracts this complexity away.

• 🧱 Official Models: Built directly on top of Google's auto-generated Pydantic models for 100% protocol compliance.
• 🚀 Developer Experience: No more manual JSON construction. Use our CheckoutBuilder to write business logic, not boilerplate.
• 🔍 Auto-Discovery: Automatically generates the /.well-known/ucp manifest based on your registered endpoints.
• 🔌 Facade Pattern: Access all complex UCP types from a single, clean import: fastucp.types.

📦 Installation

Requires Python 3.10+

# Using pip
pip install fastucp-python

# Using uv (Recommended)
uv add fastucp-python

⚡️ Quick Start

Here is a minimal Merchant Server ("Hello World") that sells a single item. FastUCP handles the manifest generation, endpoint routing, and protocol headers automatically.

# main.py
from fastucp import FastUCP
from fastucp.shortcuts import CheckoutBuilder
from fastucp.types import CheckoutCreateRequest

# 1. Initialize the App
app = FastUCP(
    title="Hello World Store", 
    base_url="http://127.0.0.1:8000"
)

@app.checkout("/checkout-sessions")
def create_session(payload: CheckoutCreateRequest):
    

    cart = CheckoutBuilder(app, session_id="demo_session_1")
    
    
    cart.add_item(
        item_id="sku_1",
        title="Hello World T-Shirt",
        price=2000, 
        quantity=1,
        img_url="https://placehold.co/400"
    )
    
    
    return cart.build()

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="127.0.0.1", port=8000)

Run the Server

python main.py

Your server is now live and UCP Compliant!

Manifest: http://127.0.0.1:8000/.well-known/ucp Checkout: http://127.0.0.1:8000/checkout-sessions

🧩 Key Features

1. The Builder Pattern Instead of dealing with nested Pydantic models like LineItemResponse(totals=[TotalResponse(...)]), you simply use:

cart.add_item(..., price=500, quantity=2)

FastUCP handles the calculations and structure for you.

2. Payment Presets Easily integrate supported payment handlers without digging into schema details:

from fastucp.presets import GooglePay

app.add_payment_handler(
    GooglePay(merchant_id="123", gateway="stripe", ...)
)

3. AI Agent Ready (MCP) FastUCP servers are designed to be easily consumed by LLM Agents (Claude, Gemini, OpenAI) via the Model Context Protocol (MCP), bridging the gap between traditional e-commerce and AI Agents.