Deep Dive into ACP and UCP: Two AI Commerce Protocols and Why Asking "Which One Is Better" Is Wrong from the Start
Comparing OpenAI and Stripe's Agentic Commerce Protocol with Google's Universal Commerce Protocol, which don't compete but operate at different layers
Stock photo for illustration only, not from the actual event
- ACP and UCP operate at different layers, with ACP focusing on product discovery and feeds, while UCP focuses on payments.
- Choosing between these two protocols is a misconception because the underlying architecture requires the exact same data management approach.
- The core challenge lies in product catalog cleanliness, not in choosing one protocol over the other.
When discussing AI-driven commerce protocols, the question often arises as to whether businesses should choose ACP or UCP. However, this perspective may not be entirely accurate, as these two protocols do not directly compete nor do they serve the same function. Protocol status data as of June 2026 illustrates this direction even more clearly.
ACP (Agentic Commerce Protocol), backed by OpenAI and Stripe, originally launched as the standard behind ChatGPT Instant Checkout before evolving in March 2026 into a discovery and feed protocol, allowing OpenAI to process which products should be displayed in ChatGPT responses.
On the other hand, UCP (Universal Commerce Protocol), backed by Google and first announced at NRF in January 2026 with further details expanded at Google Marketing Live on May 20, 2026, focuses on an end-to-end AI payment standard covering everything from search and cart creation to transactions, with announced integrations across AI Mode, Gemini, YouTube Shopping, and Gmail.
Understanding the context of both protocols provides a clear picture: ACP acts to tell AI systems what products you sell, while UCP helps AI systems purchase those products. Crucially, neither protocol takes over the transactional relationship; business owners remain the merchant of record as before. What changes is the point where purchase intent is captured and utilized.
Viewing this as a choice between one or the other is a misconception. When distilling the technical requirements of both protocols, what store backend systems need to prepare turns out to be nearly identical, involving product catalog management much more than the protocol itself.
Stock photo illustration, not from actual events
Preparation guidelines can be broken down into the following main steps:
- Phase 0 - Foundation: Improve crawler accessibility and manage Product + Offer data structures to render server-side with availability status.
- Phase 1 - ACP Feed Setup: Publish product feeds according to the ACP standard, which requires less effort and reaches ChatGPT's massive user base.
- Phase 2 - UCP Manifest Preparation: Publish the /.well-known/ucp file, generate ECDSA signing keys, and verify profile correctness.
- Phase 3 - Payment System Decision: Define policies and restrictions to allow agents to successfully complete transactions on behalf of customers.
A critical technical point to keep in mind is that agents operating via server-side protocols cannot tokenize credit cards because Stripe's process requires a browser context supporting PCI-compliance, such as Stripe.js or Payment Element, which conflicts with direct backend tool call operations. Current agentic checkout systems therefore rely on offline methods, invoices, customer-bound tokens, or redirecting to a checkout page in the final step.
Source: Dev.to
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