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Seneschal Builder Bids & Proposer Payment Export
x402
Seneschal Builder Bids & Proposer Payment Export is a paid API for AI agents from api.seneschal.space, paid per call via x402, $0.05/call, status down (last checked 2026-10-30).
Returns per-slot Ethereum block builder bids and realised proposer payments (priority + coinbase fees) as CSV or JSON lines over a specified block range or rolling time window
Price / call$0.05
Success—
StatusDown
How this service works
Pay-per-call services for the agent economy: a webhook the moment a Monero or Zcash payment lands at your address (view-key only), single-fact x402 data APIs, a paid public notice board, a stablecoin gas paymaster and a permissionless Ethereum block builder. No account, no API key — pay in USDC on Base or in XMR/ZEC.
Output
A CSV (or JSONL) file with one row per slot containing: block number, timestamp (ms and ISO), miner address, winning builder address, actual total ETH paid to proposer (priority + coinbase), priority ETH, coinbase ETH, the shadow bid in ETH, a boolean indicating whether the shadow bid would have won, and transaction count per block.
Example use cases
Audit MEV payments last 30 days
“Grab me all the Seneschal proposer payment data for the last 30 days as JSONL — I want to compare what builders actually bid in the shadow recorder versus what proposers really received in priority fees and coinbase transfers, so I can audit whether any slots look suspicious.”
Backtest builder competition strategy
“Download the per-slot builder bid and proposer payment history from Seneschal for blocks 20500000 to 20600000 as a CSV — I need the winning builder address, the shadow bid, and the actual ETH paid each slot so I can backtest a strategy around builder competition patterns.”
Identify top-earning proposer slots
“Fetch me the Seneschal block builder data for the past week in JSONL format — I want to rank slots by total ETH earned by the proposer and see which builders won the most competitive slots during that period.”
Technical details
Endpoint
GEThttps://api.seneschal.space/v1/premium/builder-bids.csv?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need bulk historical or recent Ethereum builder bid and proposer payment data across many slots for analysis, backtesting, or audit. For a single live slot or real-time tail, prefer the cheaper /v1/q/proposer-payment endpoint. Choose CSV output for spreadsheet import or JSONL for streaming pipelines.
Side effects
- Block range exceeds 100,000 blocks — returns error requiring narrower range
- window_ms exceeds 30 days (2,592,000,000 ms) — returns error
- Missing both from_block/to_block and window_ms — ambiguous query
- from_block greater than to_block — invalid range error
- Payment not included or insufficient — 402 Payment Required
- Data not yet available for very recent blocks — empty or partial result
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": "block,ts_ms,iso_time,miner,builder,actual_total_eth,actual_priority_eth,actual_coinbase_eth,shadow_bid_eth,would_have_won,tx_count\n25009771,1777754812618,2026-05-02T...,0x4838...,beaverbuild,0.066254941,0.066254941,0.000000000,0.072000000,true,343\n"
}Tags
x402
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