{"uid":"cap_11qBIPu1rONG4YUvaQjbk","slug":"mev-boost-block-payment-lookup-via-flashbots-relay-f3aa3a22","name":"MEV-Boost Block Payment Lookup via Flashbots Relay","description":"Look up the MEV-Boost payment for a specific slot or block number via the Flashbots relay. Returns the builder, proposer, value paid in ETH, gas usage, and tx count. Returns found=false if the block was built locally or via a different MEV-Boost relay (Flashbots is one of several).","url":"https://agent402.tools/api/mev-block-payment","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"slot":{"type":"number","description":"Beacon chain slot number (one of slot/blockNumber required)."},"blockNumber":{"type":"number","description":"Execution layer block number (one of slot/blockNumber required)."}}},"responseSchema":{"type":"json","example":{"slot":12345678,"found":true,"numTx":187,"relay":"flashbots","gasUsed":14987654,"gasLimit":30000000,"valueEth":0.072345,"valueWei":"72345000000000000","blockHash":"0xabc...","blockNumber":22000000,"builderShort":"0x90000000…abcdef","builderPubkey":"0x9000...","proposerPubkey":"0xa000...","proposerFeeRecipient":"0x1234..."}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","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":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_qbkJxpCN1q7TrzIBOL8UL","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Looks up the MEV-Boost payment details for a specific Ethereum beacon chain slot or execution layer block number via the Flashbots relay, returning builder, proposer, ETH value paid, gas usage, and transaction count.","exampleAgentPrompt":"What was the MEV-Boost payment for Ethereum slot 8900000? I want to know who the builder and proposer were, how much ETH was paid, and the gas usage.","exampleUseCases":null,"resultDescription":"Returns a JSON object with: found (boolean indicating if the block was relayed via Flashbots), builder address, proposer address, ETH value paid to the proposer, gas used, gas limit, and transaction count. Returns found=false if the block was built locally or via a different MEV-Boost relay.","failureModes":["found=false returned when block was built locally or via a non-Flashbots relay","Neither slot nor blockNumber provided — API requires at least one","Invalid slot or block number format causing a 400 error","Block too recent and not yet indexed by the Flashbots relay","Flashbots relay temporarily unavailable causing timeout or 5xx error"],"whenToPreferThis":"Use this endpoint when you need to investigate MEV-Boost payment data for a specific Ethereum block or beacon chain slot and want Flashbots relay-specific data including builder/proposer identities, ETH value, and gas metrics. Prefer this over on-chain explorers when you need structured, machine-readable MEV relay data without parsing raw blockchain transactions.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-13T12:42:36.329Z","isFirstParty":false}