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MEV-Boost Block Payment Lookup via Flashbots Relay
x402
MEV-Boost Block Payment Lookup via Flashbots Relay is a paid API for AI agents from agent402.tools, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).
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.
Price / call$0.002
Success—
StatusUnknown
How this service works
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).
Output
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.
Example use cases
Example prompt
“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.”
Technical details
Endpoint
POSThttps://agent402.tools/api/mev-block-paymentWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| slot | number | Beacon chain slot number (one of slot/blockNumber required). |
| blockNumber | number | Execution layer block number (one of slot/blockNumber required). |
Output
Schema · Response
{
"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..."
}
}Tags
x402
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