UCP is genuinely interesting, but I think it mostly trades one form of lock-in for another. Google and Shopify are pushing protocols like UCP and ACP because they can see AI eating the marketplace middleman. As discovery and checkout move into conversational interfaces, Google Shopping and Shopify’s own “Shop” app are at risk, and UCP is a way for them to stay central in that shift.

The issue is that UCP mainly benefits platforms that are already part of that ecosystem. Instead of Amazon et al controlling discovery, you risk ending up with Google and Shopify doing it through AI-driven interfaces. The experience looks more open, but control still sits with a small number of large platforms.

I’m working on something similar with a different premise. We’re building an open-source marketplace stack, basically a Shopify per vertical, where sellers run their own storefronts and discovery happens directly against the shop’s own API. You can see a working interoperable marketplace here[0], built on our first Shopify alternative, Openfront. Our website[1] goes deeper into the different vertical marketplaces we’re building like hotels, grocery stores, etc. We started with MCP-UI[2] for native conversational commerce, and V2 will support UCP, but it’s optional rather than the foundation.

[0] https://marketplace.openship.org

[1] https://openship.org

[2] https://mcpui.dev

Cool, congrats! Curious, how did you crawl the Shopify catalog?

It seems Shopify's big play in this is data syndication; they're pushing product data to AI companies before their competitors, and offering it as a service to non-Shopify stores (with their 'agentic plan' which launches soon). It adds a reason for new stores to pick Shopify, and they form relationships with existing non-Shopify stores?

That said, product/catalog discovery is on the UCP roadmap, and it seems you've been able to do it quickly, so I wonder how big their moat really is...

Would love to chat more about it!