ACP vs UCP vs AP2 vs MCP vs x402
Last verified 2026-06-10The agentic commerce standards, side by side. Filter to the ones you care about. Every row is sourced and carries a verification date because this space changes weekly.
Short answer: these five standards solve different layers. MCP connects agents to tools and data. ACP carries product discovery in the current ChatGPT commerce experience; its former native Instant Checkout flow ended in March 2026 (OpenAI + Stripe). UCP covers the full shopping journey; Google announced it for a future checkout rollout on AI Mode and Gemini. AP2 authorizes agent-led payments across networks (Google, extends MCP and A2A). x402 moves stablecoins natively over HTTP. They interoperate more than they compete.
| Criterion | ACP | UCP | AP2 | MCP | x402 |
|---|---|---|---|---|---|
| Author / steward | OpenAI and Stripe | Google and Shopify (+ Etsy, Wayfair, Target, Walmart) | Google, then FIDO Alliance (Apr 2026) | Anthropic, now Linux Foundation (AAIF) | Coinbase, now x402 Foundation |
| Announced | 29 Sep 2025 | 11 Jan 2026 | 16 Sep 2025 | 25 Nov 2024 | 6 May 2025 |
| Open-source status | Open source, Apache 2.0 | Open source, Apache 2.0 | Open specification (public GitHub) | Open source, MIT | Open source, Apache 2.0 |
| What it is | Agent checkout / commerce protocol | Full-journey agentic commerce standard | Agent payments framework | Agent-to-tool/data context layer | HTTP-native payment protocol |
| Payment type | Card and existing processors (Stripe SPT) | Payment Token Exchange; Google Pay at launch (PayPal announced) | Payment-agnostic (cards, stablecoins, bank transfers) | None (not a payment protocol) | On-chain stablecoins (EIP-3009) |
| Transport | HTTP (OpenAPI); MCP since 2026-04-17 | Transport-agnostic: REST, MCP or A2A | Extension of A2A and MCP | JSON-RPC 2.0 (stdio, HTTP) | HTTP 402; also MCP and A2A |
| Primary use | Product discovery in ChatGPT; checkout on the merchant side | Agentic checkout on Google AI Mode and Gemini | Authorize agent-led payments across platforms | Connect agents to tools and data | Pay per API call / resource autonomously |
| Notable adoption | OpenAI, Stripe, Etsy, Shopify (coming) | Google, Shopify, Etsy, Wayfair, Target, Walmart; 20+ endorsers | Mastercard, PayPal, Amex, Adyen, Coinbase | Claude, Cursor, Copilot, Gemini, VS Code, ChatGPT | AWS, Anthropic, Circle, NEAR |
| Latest verified proof | Spec v2026-04-17 (cart, feed, orders, MCP) | Latest reviewed release v2026-08-25 on GitHub | 60+ launch partners (Sep 2025) | Founding technical contribution to Linux Foundation AAIF (9 Dec 2025) | Apache 2.0; moved to x402 Foundation |
Table last verified .
Focused comparisons: ACP vs UCP · ACP vs AP2 · ACP vs MCP · UCP vs AP2 · ACP vs x402 · AP2 vs MCP · MCP vs A2A · x402 vs AP2 · MPP vs x402 · AP2 vs Mastercard Agent Pay · Visa TAP vs Agent Pay