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Beauty & Personal Care · x402 · early usage

Look up the MEV-Boost payment for a specific slot or block number via the Flashbots relay

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 (Flashb…

by agent402.tools · discovered, not yet claimed by its owner · updated 2026-10-08

30d calls5
30d payers3
MethodPOST
Outputjson

Mirrored from Coinbase's public x402 Bazaar. The description is the provider's own text and has not been reviewed here; the payment requirements are copied as published.

What it does

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).

Tags: crypto · mev · flashbots · block-payment · lookup · bazaar · builder-code · payment-identifier

Call contract

Method
POST
Input
json
Output
json
Last paid call
2026-10-08
Input example from Bazaar metadata
{
  "blockNumber": 26104983
}
Output example
{
  "blockHash": "0x29b12476c4bdbad3d080057a7c068c42da781d4bfb1545491d65b9f942a20461",
  "blockNumber": 26104983,
  "builderPubkey": "0x89057b5818abfca92fb9d38ea74dfab0f6f58630b6138e4f73da26666295e047cb18d353a134c5fad672eba231ff610c",
  "builderShort": "0x89057b58…ff610c",
  "found": true,
  "gasLimit": 60000000,
  "gasUsed": 14100104,
  "numTx": 144,
  "proposerFeeRecipient": "0xd4E96eF8eee8678dBFf4d535E033Ed1a4F7605b7",
  "proposerPubkey": "0xb6ab19ca47a0b0f67e95e4cbb772fd8feff2a4f481eb494a06d54308f7fa959ee87889e2ffbe34ee8d466ed47a7d5dbd",
  "relay": "flashbots",
  "slot": 15343686,
  "valueEth": 0.009667520599769124,
  "valueWei": "9667520599769125"
}

Use with an agent

  1. Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
  2. Inspect. Fetch /resources/27968.json for the price and payment options.
  3. Pay. Call GET https://agent402.tools/api/mev-block-payment. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
  4. Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, Polygon, Arbitrum One, eip155:143, Avalanche, eip155:1329, Optimism, eip155:4663, eip155:42220, Solana, stellar:pubnet, algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price
$0.002 / request
Protocol
x402 v2
Auth
No account or API key. Pay per request.
Networks
Base, Polygon, Arbitrum One, eip155:143, Avalanche, eip155:1329, Optimism, eip155:4663, eip155:42220, Solana, stellar:pubnet, algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=
Demand
5 calls · 3 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

SchemeNetworkAssetAmountPay toTimeout
exactBase
eip155:8453		USDC$0.0020xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactPolygon
eip155:137		USDC$0.0020xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactArbitrum One
eip155:42161		USDC$0.0020xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:143
eip155:143		0x754704Bc059F8C67012fEd69BC8A327a5aafb60320000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactAvalanche
eip155:43114		0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E20000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:1329
eip155:1329		0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf4239220000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactOptimism
eip155:10		0x0b2C639c533813f4Aa9D7837CAf62653d097Ff8530000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:4663
eip155:4663		0x5fc5360D0400a0Fd4f2af552ADD042D716F1d16820000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exacteip155:42220
eip155:42220		0xcebA9300f2b948710d2653dD7B07f33A8B32118C20000xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
uptoBase
eip155:8453		USDC$0.0020xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0300s
exactSolana
solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp		USDC$0.002J7aN3PLJnTCF5qpEnvJHJsnCjcGuqC2rYtEM8Gv3xwg300s
exactstellar:pubnet
stellar:pubnet		CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI7520000GDNJXCKW7ZM7GEEVP674TWPU26YJNBQ2FI4ZIPRKTPTNUEJMDHFJWWRL300s
exactalgorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=
algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=		315667042000C7IIHG7SPLPZ5H7ZT6HW3UV2OQMQQE6Y2HBNGZXSLRJULE42BEE2OY2XIE300s
accepts[] (raw JSON)
[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "2000",
    "amountUsd": 0.002,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:137",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "amount": "2000",
    "amountUsd": 0.002,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42161",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "amount": "2000",
    "amountUsd": 0.002,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:143",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x754704Bc059F8C67012fEd69BC8A327a5aafb603",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:43114",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:1329",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf42392",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:10",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85",
    "amount": "3000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:4663",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x5fc5360D0400a0Fd4f2af552ADD042D716F1d168",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42220",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0xcebA9300f2b948710d2653dD7B07f33A8B32118C",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "upto",
    "network": "eip155:8453",
    "payTo": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "2000",
    "amountUsd": 0.002,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "J7aN3PLJnTCF5qpEnvJHJsnCjcGuqC2rYtEM8Gv3xwg",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "2000",
    "amountUsd": 0.002,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "stellar:pubnet",
    "payTo": "GDNJXCKW7ZM7GEEVP674TWPU26YJNBQ2FI4ZIPRKTPTNUEJMDHFJWWRL",
    "asset": "CCW67TSZV3SSS2HXMBQ5JFGCKJNXKZM7UQUWUZPUTHXSTZLEO7SJMI75",
    "amount": "20000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "algorand:wGHE2Pwdvd7S12BL5FaOP20EGYesN73ktiC1qzkkit8=",
    "payTo": "C7IIHG7SPLPZ5H7ZT6HW3UV2OQMQQE6Y2HBNGZXSLRJULE42BEE2OY2XIE",
    "asset": "31566704",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)
{
  "properties": {
    "example": {
      "properties": {
        "blockHash": {
          "type": "string"
        },
        "blockNumber": {
          "type": "integer"
        },
        "builderPubkey": {
          "type": "string"
        },
        "builderShort": {
          "type": "string"
        },
        "found": {
          "type": "boolean"
        },
        "gasLimit": {
          "type": "integer"
        },
        "gasUsed": {
          "type": "integer"
        },
        "numTx": {
          "type": "integer"
        },
        "proposerFeeRecipient": {
          "type": "string"
        },
        "proposerPubkey": {
          "type": "string"
        },
        "relay": {
          "type": "string"
        },
        "slot": {
          "type": "integer"
        },
        "valueEth": {
          "type": "number"
        },
        "valueWei": {
          "type": "string"
        }
      },
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}
Example shape — generated from the schema, not a captured live response
{
  "example": {
    "blockHash": "string",
    "blockNumber": 0,
    "builderPubkey": "string",
    "builderShort": "string",
    "found": true,
    "gasLimit": 0,
    "gasUsed": 0,
    "numTx": 0,
    "proposerFeeRecipient": "string",
    "proposerPubkey": "string",
    "relay": "string",
    "slot": 0,
    "valueEth": 0,
    "valueWei": "string"
  },
  "type": "string"
}

Examples

curl
curl -X POST 'https://agent402.tools/api/mev-block-payment' -H 'Content-Type: application/json' --data '{"blockNumber":26104983}'
# -> 402 Payment Required; read PAYMENT-REQUIRED
# retry the identical request with PAYMENT-SIGNATURE
JavaScript
const res = await fetch("https://agent402.tools/api/mev-block-payment", {
  "method": "POST",
  "headers": {
    "content-type": "application/json"
  },
  "body": "{\"blockNumber\":26104983}"
});
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}
Python
import httpx
import json
res = httpx.request("POST", "https://agent402.tools/api/mev-block-payment", json=json.loads("{\"blockNumber\":26104983}"))
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider
agent402.tools
Endpoint
https://agent402.tools/api/mev-block-payment
Machine-readable
/resources/27968.json