{"uid":"cap_FD1-z3eD1untG-n0C5AOK","slug":"seneschal-private-relay-ethereum-private-transaction-submission-6d8f122d","name":"Seneschal Private Relay — Ethereum Private Transaction Submission","description":"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.","url":"https://api.seneschal.space/v1/premium/private-relay","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"raw_tx":{"type":"string","description":"Your locally-signed raw transaction (0x-prefixed). Sign offline; never send a private key."}}},"responseSchema":{"type":"json","example":{"ok":true,"to":"0x…","from":"0x…","note":"Submitted privately; never entered the public mempool. Watch tx_hash for inclusion.","tx_hash":"0xabc…","accepted":["seneschal-rbuilder","flashbots","titan"],"chain_id":1,"rejected":[],"public_mempool":false}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.5","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":"$0.5/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.5","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.5","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_nWWoBc6-rRXisuduEd7ql","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.5","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Submits a locally-signed raw Ethereum transaction privately to block builders, bypassing the public mempool to prevent frontrunning and sandwich attacks.","exampleAgentPrompt":"Submit this signed raw Ethereum transaction privately through Seneschal's private relay so it never hits the public mempool — here's the hex: 0x02f87a01...","exampleUseCases":[{"title":"MEV-protected DeFi swap","prompt":"I've got a large Uniswap swap signed and ready as a raw hex transaction — can you relay it privately through Seneschal so MEV bots can't frontrun or sandwich me? The raw tx is 0x02f87a018459682f00..."},{"title":"Private NFT mint submission","prompt":"Submit my locally-signed NFT mint transaction privately so it doesn't get sniped in the mempool. I have the signed hex ready: 0x02f8ac01849502f9..."},{"title":"Stealth liquidation transaction","prompt":"I need to submit this liquidation transaction without anyone seeing it in the mempool first — relay it through the Seneschal private relay for me: 0x02f87b01843b9aca00..."}],"resultDescription":"A JSON object confirming whether the transaction was accepted, the resulting transaction hash, the list of block builders that accepted or rejected it, and a confirmation that the transaction never entered the public mempool.","failureModes":["Malformed or improperly signed raw transaction rejected by all builders","Transaction already mined or nonce too low","Chain ID mismatch causing rejection","All target builders reject the transaction (rejected list populated, accepted empty)","Payment failure via x402/USDC prevents relay attempt","Transaction too large or gas limit exceeded"],"whenToPreferThis":"Choose this endpoint when you need to submit an Ethereum transaction without any public mempool exposure — particularly for large DeFi trades vulnerable to MEV, liquidations where timing secrecy matters, or any transaction where frontrunning or sandwich attacks are a risk. Unlike direct Flashbots submission, this routes through multiple builders (Flashbots, Titan, Seneschal's own rbuilder) simultaneously and requires no API key — pay per call with USDC on Base.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T06:41:56.144Z","isFirstParty":false}