Universal Commerce Protocol: Open standard for agentic commerce interoperability(a2aprotocol.ai)
a2aprotocol.ai
Universal Commerce Protocol: Open standard for agentic commerce interoperability
https://a2aprotocol.ai/blog/2026-universal-commerce-protocol
3 comments
Nice to see an open standard for this instead of proprietary integrations.
Made a validator at ucptools.dev to help with implementation - checks the full spec compliance and tells you exactly what to fix.
The /.well-known/ucp pattern is smart - same discovery mechanism as security.txt, apple-app-site-association, etc.
Made a validator at ucptools.dev to help with implementation - checks the full spec compliance and tells you exactly what to fix.
The /.well-known/ucp pattern is smart - same discovery mechanism as security.txt, apple-app-site-association, etc.
The protocol uses a capability-based architecture where businesses publish their supported features at `/.well-known/ucp`, and platforms negotiate capabilities automatically during request/response flows. Core capabilities include checkout sessions (`dev.ucp.shopping.checkout`), order lifecycle management (`dev.ucp.shopping.order`), and OAuth 2.0-based identity linking.
Co-developed by Google, Shopify, Etsy, Wayfair, Target, and Walmart, with support from 60+ organizations including Stripe, PayPal, and Visa. Transport-agnostic design supports REST APIs, MCP for LLM integration, and A2A for agent-to-agent communication.
The article covers architecture, core capabilities, extensions, payment architecture, and integration patterns. Includes code examples and implementation details.