ACP vs UCP: Which Protocol Does Your Store Need?

Stores that support both ACP and UCP see up to a 40% increase in agent-driven traffic — because every major AI shopping surface speaks at least one of these protocols.

Dimension ACP (Agent Commerce Protocol) UCP (Universal Checkout Protocol)
Scope Full lifecycle — discovery through post-purchase Checkout-focused — intent to order confirmation
First surface Product catalog & search Cart or buy-now intent
Transport REST + WebSocket for real-time events REST only, stateless request/response
Discovery Built-in product search & filtering API External — relies on existing catalog feeds
Checkout flow Multi-step with cart, shipping, tax, payment stages Single-call checkout with pre-computed totals
State machine Explicit states: browse → cart → checkout → confirm Minimal: intent → order → fulfilled
Escalation Built-in human handoff at any stage Redirect URL for edge cases
Payment Tokenized via provider SDK (Stripe, Adyen, etc.) Merchant-managed payment links & tokenization
Error model Typed error codes with recovery suggestions HTTP status codes with JSON error body
Auth OAuth 2.0 with agent-specific scopes API key or mutual TLS
Post-purchase Returns, tracking, reviews, and reorders Order status polling; returns via separate API
Update method Push via WebSocket + webhook fallback Webhook-only notifications
Versioning URL-path versioning (e.g., /v2/) Header-based versioning (Accept header)
Data format JSON-LD with Schema.org product annotations Plain JSON with OpenAPI spec
Backers Shopify, OpenAI, large marketplace consortiums Stripe, indie platforms, headless commerce vendors

When to Use Which

Choose ACP first if…

  • • You have a large catalog and want agents to search & filter natively
  • • Your checkout involves complex multi-step flows (e.g., custom products, subscriptions)
  • • You need real-time inventory and pricing pushed to agents
  • • Post-purchase features (returns, reorders) are a competitive advantage

Choose UCP first if…

  • • You already have product feeds on Google, Meta, or affiliate networks
  • • You want the fastest integration — a single endpoint to go live
  • • Your payment stack is Stripe or a provider with built-in tokenization
  • • You sell across multiple storefronts and need a unified checkout handshake

Choose both if…

  • • You want maximum coverage across every AI shopping surface
  • • Your traffic mix includes both discovery-first and buy-now agents
  • • You're building a platform and need to offer protocol choice to merchants
  • • You want to validate both protocols in one pass — Prova tests ACP and UCP endpoints side by side

Related: What is Agentic Commerce? · Agentic Commerce Glossary

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Your agents are already shopping. Is your checkout ready?

Agent-driven commerce traffic is projected to grow 1,200% over the next two years. Businesses that aren't ready will lose sales to those that are. Prova gives your checkout the machine-readable layer it needs so AI agents can discover, validate, and complete purchases — without friction.

MCP & A2A protocols supported Sandbox-only environment SOC 2 compliance planned