{"uid":"cap_1gKEWTAhpIiPKTzHx2me0","slug":"x402-seller-playbook-b015af46","name":"x402-seller-playbook","description":"The seller's playbook for a live x402 endpoint: the exact 402 challenge to serve (v2 header and v1 body in one response), what the facilitator /verify really checks and the balance rule that rejects a valid signature, how a settled payment becomes a delivery, delivery evidence in three independent records, how to get listed where agent buyers search, and a plain-USDC page for human buyers who will never read a 402. Delivered as the full text plus a signed, expiring PDF download link. One GET, one delivery, no live upstream call, and the free sample at /guide/sample carries the whole protocol before you pay. The same playbook also covers the receiving side: USDC on Base with no account, no KYC and no third party between you and the buyer. A purchase is two calls by design: this first call returns 402 with the price and the payment terms, and you then repeat the same request with the PAYMENT-SIGNATURE header to receive the 200 delivery.","url":"https://x402-catalog-history.ai-business-surface.workers.dev/guide?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"3","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.25/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.25","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.25","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_FDQwJNaNiHDRG9HhEy_gN","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.25","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Delivers a comprehensive guide for building and operating x402-protocol payment-gated endpoints, including 402 challenge format, facilitator verification rules, delivery evidence, and USDC receiving setup on Base.","exampleAgentPrompt":"I want to build a paid API endpoint using the x402 protocol — can you fetch the full seller playbook so I know exactly what 402 challenge to serve, how the facilitator checks the payment, and how to receive USDC on Base without an account?","exampleUseCases":[{"title":"Building first x402 payment-gated endpoint","prompt":"I'm setting up my first x402 endpoint and I don't know what the 402 challenge response is supposed to look like — can you get me the seller playbook so I understand the v2 header and v1 body format and how the facilitator verifies signatures?"},{"title":"Listing API for agent buyer discovery","prompt":"I've got a working x402 endpoint but I want agent buyers to be able to find it — can you pull the playbook so I can see how to get listed where agents search and what the plain-USDC fallback page for human buyers should look like?"},{"title":"Receiving USDC on Base without KYC","prompt":"I want to start accepting USDC payments on Base with no account setup and no third party taking a cut — can you fetch the x402 seller guide so I understand exactly how the receiving side works and what delivery evidence I need to keep?"}],"resultDescription":"Full text of the x402 seller playbook covering: exact 402 challenge format (v2 header + v1 body), facilitator /verify logic and balance-rule edge cases, how payment settlement triggers delivery, three independent delivery evidence records, instructions for listing the endpoint in agent discovery directories, a plain-USDC human buyer page guide, and USDC-on-Base receiving setup with no account or KYC. Also includes a signed, expiring PDF download link. A free sample of the full protocol is available at /guide/sample before purchasing.","failureModes":["Missing or invalid PAYMENT-SIGNATURE header on second call returns 402 with payment terms rather than 200 delivery","Expired or reused payment signature rejected by facilitator — buyer must generate a fresh signature","Insufficient USDC balance on buyer wallet causes facilitator to reject even a cryptographically valid signature","PDF download link expires after a fixed time window — must re-purchase to get a fresh link","Endpoint returns no live upstream call, so content is static; may not reflect protocol updates in real time"],"whenToPreferThis":"Choose this endpoint when you need authoritative, step-by-step operational guidance for implementing the x402 payment protocol on the seller side — particularly when you need the exact 402 response format, facilitator verification semantics, and USDC-on-Base receiving setup in one document. Prefer this over generic blockchain payment guides or x402 spec documents when you want practical implementation details including discovery listing and human buyer fallback strategies.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-18T00:30:49.171Z","isFirstParty":false,"canonicalSlug":"x402-seller-playbook-b015af46"}