Agentic CommerceThe comparison table
| UCP | ACP | MCP | AP2 | |
|---|---|---|---|---|
| Backed by | Google × Shopify + retail coalition | OpenAI × Stripe (+ Meta) | Anthropic (industry-wide adoption) | Google + card networks |
| Launched | January 2026 | September 2025 | November 2024 | September 2025 |
| Layer | Commerce (full journey) | Commerce (conversational checkout) | Model ↔ system connection | Payments (mandates) |
| Flagship surface | Google AI Mode, Gemini, Copilot | ChatGPT (Instant Checkout) | All compatible agents | Cross-cutting |
| Model | Open (Apache 2.0) | Open; ~4% commission on Instant Checkout | Open | Open |
| Merchant's task | Publish a capability profile | Product feed + payment integration | Expose an MCP server | Carried by payment providers |
Who does what: the full stack
The only genuine rivalry sits on the top layer, between UCP and ACP — two coalitions, two dominant surfaces (Google and ChatGPT). Even that is relative: both specifications converged through 2026 on the same concepts (capability negotiation, product feeds, delegated payment), both can build on MCP, and Stripe, Visa and Mastercard appear on both sides. The likeliest outcome isn't one standard winning, but a common data foundation serving several protocols.
Which combination fits your profile
- B2C merchant on a platform (Shopify, BigCommerce…) — UCP and ACP arrive natively: your work isn't protocol-level, it's catalog and feed quality, which determines your visibility on both surfaces.
- Direct-to-consumer brand — Both protocols let you be buyable outside marketplaces: start with the product feed (shared), then enable ACP for ChatGPT and UCP through Merchant Center.
- B2B merchant or platform — An MCP server is your best entry point: it natively handles per-account authentication, hence negotiated pricing — something consumer surfaces don't yet cover. UCP (account linking) becomes relevant next, and AP2 will underpin autonomous replenishment.
- Custom platform — Implement capability by capability, starting with discovery (UCP) or read-only (MCP): immediate visibility, zero risk.
Frequently asked questions
Should I wait for a standard to win?
No, because the useful work is common to all four: reliable product data, clean feeds, a structured catalog, readable terms of sale. That foundation serves any protocol — and your human customers today.
Where do I start on a limited budget?
Structured data and product feeds: the prerequisite for all four protocols and the best effort-to-visibility ratio. Protocol implementation comes after — and often your platform supplies it.