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Documentation Index

Fetch the complete documentation index at: https://developers.fd.xyz/llms.txt

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Multiple companies are building protocols for AI agent commerce — each covering a different part of the journey from product discovery to payment. Prism is protocol-agnostic: you integrate once, and Prism handles protocol translation behind the scenes. When a new protocol gains traction, Prism adds support without changing your integration.

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The Protocol Landscape

LayerProtocolCreated ByStatus
Settlement (payment)x402Coinbase (open standard)Live — Prism uses this today
Checkout (transaction)ACPOpenAILive — Prism supports this today
Full Commerce JourneyUCPGoogleLive — Prism supports this today
These protocols are complementary, not competing. x402 handles the settlement layer — the actual movement of money. ACP and UCP handle the commerce layer — product discovery, cart management, checkout flow. An agent might use ACP to find and select a product, then x402 (via Prism) to pay for it.

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x402 — Settlement Protocol

x402 implements the HTTP 402 “Payment Required” status code for machine-to-machine stablecoin payments. It’s Prism’s primary protocol today. How it works: Agent requests a resource → server responds 402 with payment requirements → agent pays on-chain → server grants access. Best for: API monetization, data feeds, premium content, pay-per-request services — any endpoint where access requires payment. Status: Live. This is what you integrate with today. Full x402 documentation →

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ACP — Agent Commerce Protocol

Created by OpenAI for structured AI agent commerce. ACP covers the full commerce journey: product discovery, cart management, checkout, payment, and order lifecycle. It’s designed for scenarios where an agent needs to browse a catalog, select products, and complete a purchase. How Prism integrates: ACP handles the commerce flow (what the agent is buying). Prism handles the settlement (how the agent pays) via the xyz.fd.prism_payment handler. Merchants get:
  • AI agents that can browse their product catalog programmatically
  • Structured checkout with stablecoin settlement via Prism
  • The same instant settlement and zero chargebacks as x402
Best for: E-commerce product purchases, multi-item orders, any scenario with a traditional checkout flow. Status: Live. Prism supports ACP via the xyz.fd.prism_payment handler today. Full ACP integration guide →

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UCP — Universal Commerce Protocol

Created by Google for the full commerce journey — from discovery to post-purchase. UCP is more comprehensive than ACP, covering the entire lifecycle: discovery, selection, purchase, fulfillment, returns, and support. How Prism integrates: Prism serves as the settlement and payment verification layer within the UCP flow. Best for: Complex multi-step purchases, scenarios requiring fulfillment tracking, subscription-like flows. Status: Live. Prism supports UCP via the xyz.fd.prism_payment handler today. Full UCP integration guide →

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How Prism Abstracts Protocol Complexity

The key insight: you integrate Prism once. Prism handles protocol translation on the inbound side. Whether an agent pays via x402, initiates checkout via ACP, or goes through a full UCP commerce journey — your SDK integration and webhook handling stay the same. This protects your investment. As the protocol landscape evolves, you don’t need to re-integrate. Prism adapts; your code doesn’t change.

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What Should I Use Today?

x402 — Start Here

x402 is live and supported today. Ideal for API monetization and pay-per-request models.

Quick Start

Integrate x402 payment protection in minutes with the Prism SDK.
If you’re building an e-commerce platform, integrate Prism now with x402, UCP, or ACP (all live today). All three protocols use the same xyz.fd.prism_payment handler and settle via the same Prism API.
Last modified on April 29, 2026