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RelayData

MEV relay connection information for Proposer-Builder Separation (PBS).

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Overview

RelayData represents MEV relay connection information used in PBS. Relays act as trusted intermediaries between block builders and validators, ensuring builders cannot see validator signatures before block delivery.

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Type Definition

type RelayDataType = {
  /** MEV relay endpoint URL */
  readonly relayUrl: string;

  /** Relay's BLS public key (48 bytes) */
  readonly relayPubkey: Uint8Array;

  /** Builder's BLS public key (48 bytes, optional) */
  readonly builderPubkey?: Uint8Array;

  /** Current consensus layer slot */
  readonly slot: SlotType;

  /** Parent block hash (32 bytes) */
  readonly parentHash: HashType;

  /** Validator fee recipient address (20 bytes) */
  readonly proposerFeeRecipient: AddressType;
};

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Well-Known Relays

import { MEV_RELAYS } from './primitives/RelayData/index.js';

MEV_RELAYS.FLASHBOTS          // "https://relay.flashbots.net"
MEV_RELAYS.BLOXROUTE_MAX_PROFIT  // "https://bloxroute.max-profit.bloxroute.com"
MEV_RELAYS.BLOXROUTE_REGULATED   // "https://bloxroute.regulated.bloxroute.com"
MEV_RELAYS.EDEN               // "https://relay.edennetwork.io"
MEV_RELAYS.MANIFOLD           // "https://mainnet-relay.securerpc.com"
MEV_RELAYS.ULTRASOUND         // "https://relay.ultrasound.money"
MEV_RELAYS.AGNOSTIC           // "https://agnostic-relay.net"

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Usage

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Create RelayData

import * as RelayData from './primitives/RelayData/index.js';
import { MEV_RELAYS } from './primitives/RelayData/index.js';

const relay = RelayData.from({
  relayUrl: MEV_RELAYS.FLASHBOTS,
  relayPubkey: new Uint8Array(48), // relay's BLS pubkey
  slot: 12345n,
  parentHash: new Uint8Array(32),
  proposerFeeRecipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
});

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Get API Endpoint

const url = RelayData.getEndpoint(relay, "/eth/v1/builder/header");
// "https://relay.flashbots.net/eth/v1/builder/header"

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API Reference

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Constructors

FunctionDescription
from(data)Create from RelayDataLike object

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Methods

FunctionDescription
getEndpoint(relay, method)Construct full API endpoint URL

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Constants

ConstantDescription
MEV_RELAYSWell-known relay endpoints

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MEV-Boost API Endpoints

Common relay API methods:
EndpointDescription
/eth/v1/builder/headerRequest block header bid
/eth/v1/builder/blinded_blocksSubmit blinded block
/eth/v1/builder/statusCheck relay status
/relay/v1/data/bidtracesQuery bid traces

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Example: Request Block Header

const endpoint = RelayData.getEndpoint(relay, "/eth/v1/builder/header");
const params = `${relay.slot}/${relay.parentHash}/${relay.proposerFeeRecipient}`;

const response = await fetch(`${endpoint}/${params}`);
const bid = await response.json();

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PBS Flow

Builder                    Relay                      Proposer
   |                         |                            |
   |--[submit block bid]---->|                            |
   |                         |--[header+bid]------------->|
   |                         |                            |
   |                         |<--[signed header]----------|
   |                         |                            |
   |<--[request payload]-----|                            |
   |--[block payload]------->|                            |
   |                         |--[full block]------------->|
  1. Builder submits block bid to relay
  2. Relay forwards best header to proposer
  3. Proposer signs header (commits to block)
  4. Relay releases block to builder
  5. Builder sends full payload
  6. Relay forwards to proposer for broadcast

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Relay Selection

Consider when selecting relays:
  • Censorship: Some relays filter transactions (OFAC compliance)
  • Reputation: Relay uptime and reliability
  • Diversity: Using multiple relays reduces centralization risk
  • Geographic: Latency affects bid competitiveness
// Use multiple relays for redundancy
const relays = [
  RelayData.from({ relayUrl: MEV_RELAYS.FLASHBOTS, ... }),
  RelayData.from({ relayUrl: MEV_RELAYS.ULTRASOUND, ... }),
  RelayData.from({ relayUrl: MEV_RELAYS.AGNOSTIC, ... }),
];

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See Also