Problem & Solution

x402 enables pay‑per‑request over HTTP via the 402 Payment Required status code. Today, merchants usually price their offers in a single asset (e.g., USDC on Base). Buyers, however, often hold other assets. Any‑Asset Routing (AAR) is a minimal, composable extension that lets a buyer “pay with what they have” while the protocol deterministically routes and settles to the merchant’s desired asset.

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AAR defines a standard handshake between client, facilitator (router), and merchant so that:

• Clients can present a RouteRequest describing what they hold and the offer they want to satisfy.

• Facilitators respond with a signed RouteQuote defining how to convert the buyer’s asset into the merchant’s accepted asset(s) within explicit constraints (amount, slippage, deadline).

• x402 receipts bind offerId + quoteId + amountOut so merchants can verify locally without bespoke integration.

• Optional staking and reputation create incentives for high‑quality routing while preserving permissionless participation.

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The result: higher conversion, lower integration cost, and a foundation for further protocol‑level features like split payouts, refunds, and streaming‑402.