ACP, UCP, MCP, AP2: one table that says who runs what
- industry
Target reader: Cross-border e-commerce founders / heads of operations · anyone drowning in protocol acronyms
Between April 2025 and January 2026, five sets of agent-commerce rails shipped, and their names could hardly look more alike. ACP and AP2 differ by one character. MCP gets misattributed daily. UCP and ACP get conflated constantly. The problem is not your memory: the buildout is moving so fast that half the industry coverage gets the names wrong.
The conclusion up front: MCP connects, AP2 authorizes, ACP checks out, UCP runs the full lane. The table below is for looking things up.
The table: five protocols, one layer each, none interchangeable
| Protocol | Published by · when | Layer | What it does |
|---|---|---|---|
| MCP | Anthropic · open-sourced Nov 2024; donated to the Agentic AI Foundation (Linux Foundation) Dec 2025 | Connection | Lets agents plug into any system — tools, databases, store backends; adopted by OpenAI, Google, Microsoft |
| AP2 | Google · Sep 2025; donated to the FIDO Alliance Apr 2026 | Payment authorization | Three signed mandates (Intent / Cart / Payment) answering "did the user really authorize this spend"; 60+ launch partners incl. Mastercard, PayPal, UnionPay International |
| ACP | OpenAI + Stripe · Sep 2025 | Checkout execution | The open-source in-conversation checkout: see a product in ChatGPT, buy without leaving the chat |
| UCP | Google · Jan 2026 | Full-lane commerce | Discovery, identity, checkout, order management in one chain; built with Shopify, Etsy, Target, Walmart and 20+ backers; open-sourced at ucp.dev |
| Agent Pay / Intelligent Commerce | Mastercard · Visa · Apr 2025 | Card-network tokens | Issues agents controllable payment credentials: spend limits, merchant scope, revocable any time |
The three most common mix-ups
- MCP is not a shopping protocol. MCP (Model Context Protocol) is connection-layer infrastructure: it solves "how does an agent plug into your system," and commerce is just one use. Open-sourced by Anthropic in November 2024, adopted by OpenAI, Google DeepMind and Microsoft through 2025, and donated to the Linux Foundation's Agentic AI Foundation in December 2025. Today it is the industry's shared foundation, not any one company's commerce stack.
- ACP is not Anthropic's. The initial misleads: ACP is the Agentic Commerce Protocol, published and open-sourced by OpenAI and Stripe on September 29, 2025. It launched with Etsy purchases inside ChatGPT, and Walmart followed with its announcement two weeks later.
- AP2 and UCP are not the same thing, though both are Google's. AP2 governs "was this payment genuinely authorized"; UCP governs "how does the whole shopping lane run end to end." Same company, two different layers, published four months apart. AP2 has since moved to FIDO Alliance stewardship (April 2026), the same neutrality logic as MCP's move to the Linux Foundation: rails only get adopted when no one owns them.
Five rails in nine months, each removing the last one's friction
Straighten the timeline and the logic fits in one sentence: each stage removes the friction of the one before it. Recommendations had no links, so links were added. Links needed a human click, so agents took over the operation. Agent operation was unreliable, so structured protocols were written. Protocols lacked payment trust, so card networks and signed credentials stepped in. The direction is monotonic: there is no node where this turns back.
Meanwhile China runs a parallel track: Qwen and Taobao fully connected in-conversation ordering in May 2026, Doubao plugged into Douyin's store, and JD began testing a standalone AI-shopping app. Platforms own their payments and fulfillment, skip protocol negotiation for vertical integration, and close the purchase path even faster. A cross-border merchant lives in both worlds at once.
For cross-border merchants: the contest is the data layer, not the protocol layer
- You don't need to pick a side. The protocol contest is fought between platforms: Shopify already supports both ACP and UCP. What merchants win or lose is the data layer.
- All five rails depend on the same input: clean, complete, machine-readable product data. Price, stock, shipping scope, specs: one broken field, and no protocol can compensate.
- Solve "does AI recommend you" before "where does checkout happen." Protocols move the transaction; first your product has to appear in the answer.
- Watch both markets. Protocol coalitions in the US and Europe, platform integration in China: two market structures, two ways in, one data foundation underneath.
Three traps to avoid
- When someone sells you "we support protocol X," ask one question: which layer, and what friction does it remove. If they can't answer, the protocol is a word on their website.
- Don't treat protocol adoption as a one-off project. Five rails shipped in nine months and the iteration hasn't slowed. A data pipeline that keeps up is worth more than any single integration.
- Don't underweight the authorization layer. AP2's mandates are an auditable authorization chain; the closer it gets to table stakes, the closer non-compliant data gets to disqualification.
The foundations of the protocol layer are being poured right now, and every rail runs on the same input: product data AI can actually read. That work can start today.
