UltraCart REST API

The UltraCart REST API v2 is the current API for all UltraCart integrations and should be used for all new development. It provides comprehensive programmatic access to your UltraCart store including orders, items, customers, checkout, fulfillment, marketing, and more.

API Reference: https://www.ultracart.com/api/

SDK Samples: https://github.com/UltraCart/sdk_samples

SDKs

Official SDKs are available for six languages. Each SDK is published to its language's standard package manager.

Language	Repository	Package

Language	Repository	Package
C#	rest_api_v2_sdk_csharp	NuGet
Java	rest_api_v2_sdk_java	Maven
JavaScript	rest_api_v2_sdk_javascript	npm
PHP	rest_api_v2_sdk_php	Packagist
Python	rest_api_v2_sdk_python	PyPI
Ruby	rest_api_v2_sdk_ruby	RubyGems

Authentication

Creating an API Simple Key — Generate a Simple API Key for server-side authentication
Creating a Browser Key for a JavaScript checkout — Set up a browser key for client-side checkout integrations

API Topics

Understanding Auto Order State — How auto order (subscription) states and transitions work
Understanding Auto Order Webhooks — Webhook events for auto order lifecycle changes
Upsells via API — Implement post-purchase upsell flows through the API
API Single Sign-On — SSO integration for UltraCart authentication
Developer Applications - OAuth Client ID and Secret — Set up OAuth credentials for third-party applications
Troubleshooting API Errors — Common API error codes and how to resolve them

Webhooks

Creating a Simple Webhook — Step-by-step guide to setting up your first webhook
Creating a Return Email Webhook — Configure webhooks for return email notifications

Sample Code

Working code samples are available for every API endpoint in 8 languages (C#, Java, JavaScript, PHP, Python, Ruby, TypeScript, and cURL). Samples are organized by API category with over 4,400 examples covering 22 API areas.

See the API Samples page for the complete reference with direct links to every sample by category and language.

If you cannot find what you need in the official API reference or samples, please email support and ask for help.

Legacy APIs

UltraCart REST API (v1) — Documentation for the original REST API. Use REST API v2 for all new development.