{"uid":"cap_wtI2dGU9QjxOeUKlujRbl","slug":"mev-boost-builder-market-share-5eb7aa32","name":"MEV-Boost Builder Market Share","description":"Builder market share aggregated over the last N MEV-Boost blocks via the Flashbots relay. Returns per-builder block count, share percent, total ETH paid to proposers, and average per block. Use to track block-builder concentration or detect a new builder gaining share.","url":"https://agent402.tools/api/mev-builder-share","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"window":{"type":"number","description":"Recent blocks to aggregate (10-200, default 100)."}}},"responseSchema":{"type":"json","example":{"relay":"flashbots","builders":[{"blocks":42,"sharePct":42,"builderShort":"0x90000000…abcdef","builderPubkey":"0x9000...","avgEthPerBlock":0.082305,"totalEthToProposers":3.456789}],"windowBlocks":100,"uniqueBuilders":5}},"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_cbfm2vRQo7zVKWjeDh4XT","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":"Aggregates block-builder market share statistics over a recent window of MEV-Boost blocks via the Flashbots relay, returning per-builder block counts, share percentages, and ETH paid to proposers.","exampleAgentPrompt":"Show me the block-builder market share and ETH paid to proposers aggregated over the last 50 MEV-Boost blocks via the Flashbots relay, so I can see if any builder is dominating or a new one is gaining ground.","exampleUseCases":null,"resultDescription":"A list of block builders with their individual block counts, market share percentage, total ETH paid to proposers, and average ETH paid per block — computed over the requested window of recent MEV-Boost blocks from the Flashbots relay.","failureModes":["window parameter out of range (must be 10-200) returns a validation error","Flashbots relay data temporarily unavailable causes a service error","payment failure or insufficient USDC balance prevents the call from completing","malformed request body returns a 400 bad request","window set too small may return noisy or unrepresentative share data"],"whenToPreferThis":"Use this endpoint when you need a quick, aggregated snapshot of Ethereum block-builder concentration from the Flashbots relay without having to query raw relay data yourself. Ideal for monitoring builder centralization trends, detecting new entrants, or computing proposer revenue statistics over a sliding window of recent blocks.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T19:14:04.384Z","isFirstParty":false}