UCP Python SDK

Official Python library for the Universal Commerce Protocol (UCP).

Overview

This repository contains the Python SDK for the Universal Commerce Protocol (UCP). It provides Pydantic models for UCP schemas, making it easy to build UCP-compliant applications in Python.

UCP Version Compatibility

Each version of the Python SDK is generated against a specific version of the UCP schema:

SDK Version	UCP Schema Version
0.4.x	2026-04-08
0.3.x	2026-01-23
0.2.x / 0.1.x	2026-01-11

Installation

To use this SDK in your own project, install it from PyPI:

pip install ucp-sdk

Or, if you are managing your project with uv:

uv add ucp-sdk

Usage

The example below parses a UCP checkout response and reads typed fields:

from ucp_sdk.models.schemas.shopping.checkout import Checkout

# Parse a UCP checkout response
checkout = Checkout.model_validate(checkout_data)

# Access typed fields
print(checkout.status)       # "incomplete" | "ready_for_complete" | ...
print(checkout.currency)     # ISO 4217 currency code
for item in checkout.line_items:
    print(f"{item.item.title}: {item.quantity}")

Available model packages

Package	Description
ucp_sdk.models.schemas.shopping	Checkout, cart, catalog, order, payment models
ucp_sdk.models.schemas.shopping.types	Line items, totals, buyer, fulfillment, signals
ucp_sdk.models.schemas.transports	REST, MCP, and embedded protocol bindings
ucp_sdk.models.schemas	Service definitions, capabilities, payment handlers

Validation

All models support Pydantic validation and serialization:

from pydantic import ValidationError
from ucp_sdk.models.schemas.shopping.checkout import Checkout

# Validate data against UCP schemas
try:
    checkout = Checkout.model_validate(checkout_data)
    # Serialize to JSON-compatible dict
    checkout_dict = checkout.model_dump(exclude_none=True)
except ValidationError as e:
    print(e.errors())

Development

Prerequisites

This project uses uv for dependency management.

Setup

# Clone the repository
git clone https://github.com/Universal-Commerce-Protocol/python-sdk.git
cd python-sdk

# Install dependencies
uv sync

Generating Pydantic Models

The models are automatically generated from the JSON schemas in the UCP Specification.

To regenerate the models:

uv sync
./generate_models.sh <version>

Where <version> is the version of the UCP specification to use (for example, "2026-04-08").

If no version is specified, the main branch of the UCP repo will be used.

The generated code is automatically formatted using ruff.

Contributing

We welcome community contributions. See our Contribution Guide for details.

License

UCP is an open-source project under the Apache License 2.0.