Submit Transaction for Relay

curl -X POST https://relay-api.hyperlane.xyz/relay \
  -H "Content-Type: application/json" \
  -d '{
    "origin_chain": "base",
    "tx_hash": "0xabc123..."
  }'

curl -X POST https://testnet-relay-api.hyperlane.xyz/relay \
  -H "Content-Type: application/json" \
  -d '{
    "origin_chain": "basesepolia",
    "tx_hash": "0xabc123..."
  }'

const response = await fetch('https://relay-api.hyperlane.xyz/relay', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    origin_chain: 'base',
    tx_hash: '0xabc123...',
  }),
});
const { messages } = await response.json();

import requests

response = requests.post('https://relay-api.hyperlane.xyz/relay', json={
    'origin_chain': 'base',
    'tx_hash': '0xabc123...',
})
messages = response.json()['messages']

{
  "messages": [
    {
      "message_id": "a1b2c3d4e5f6...",
      "origin": 8453,
      "destination": 1,
      "nonce": 42
    }
  ]
}

{
  "messages": []
}

"origin_chain cannot be empty"

"Transaction already submitted recently"

"Request timeout"

POST

relay

curl -X POST https://relay-api.hyperlane.xyz/relay \
  -H "Content-Type: application/json" \
  -d '{
    "origin_chain": "base",
    "tx_hash": "0xabc123..."
  }'

curl -X POST https://testnet-relay-api.hyperlane.xyz/relay \
  -H "Content-Type: application/json" \
  -d '{
    "origin_chain": "basesepolia",
    "tx_hash": "0xabc123..."
  }'

const response = await fetch('https://relay-api.hyperlane.xyz/relay', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    origin_chain: 'base',
    tx_hash: '0xabc123...',
  }),
});
const { messages } = await response.json();

import requests

response = requests.post('https://relay-api.hyperlane.xyz/relay', json={
    'origin_chain': 'base',
    'tx_hash': '0xabc123...',
})
messages = response.json()['messages']

{
  "messages": [
    {
      "message_id": "a1b2c3d4e5f6...",
      "origin": 8453,
      "destination": 1,
      "nonce": 42
    }
  ]
}

{
  "messages": []
}

"origin_chain cannot be empty"

"Transaction already submitted recently"

"Request timeout"

Submit an on-chain transaction for fast relay. The relayer extracts any Hyperlane messages from the transaction, filters to eligible messages (currently CCTP V2 only), and immediately enqueues them for delivery — bypassing the normal block-polling delay.

Non-eligible messages (e.g. non-CCTP V2) are silently skipped. The response only contains messages that were accepted. An empty messages array means the transaction contained no eligible Hyperlane messages.

Show Request Body

origin_chain

string

required

The canonical chain name of the origin chain (e.g. "ethereum", "base"). Must be 1–128 characters.

tx_hash

string

required

Hex-encoded transaction hash on the origin chain, with or without 0x prefix. Must be 1–512 characters.

Show Response Body

messages

MessageInfo[]

Array of accepted messages that were enqueued for relay. Empty if no eligible messages were found.

Show MessageInfo

message_id

string

Hex-encoded Hyperlane message ID (without 0x prefix).

origin

number

Origin chain domain ID (u32).

destination

number

Destination chain domain ID (u32).

nonce

number

Message nonce (u32).

Hyperlane hosts public relay API endpoints:

Mainnet: https://relay-api.hyperlane.xyz/relay
Testnet: https://testnet-relay-api.hyperlane.xyz/relay

For self-hosted relayers, replace the URL with your relayer’s address (default: http://localhost:9090/relay).

curl -X POST https://relay-api.hyperlane.xyz/relay \
  -H "Content-Type: application/json" \
  -d '{
    "origin_chain": "base",
    "tx_hash": "0xabc123..."
  }'

curl -X POST https://testnet-relay-api.hyperlane.xyz/relay \
  -H "Content-Type: application/json" \
  -d '{
    "origin_chain": "basesepolia",
    "tx_hash": "0xabc123..."
  }'

const response = await fetch('https://relay-api.hyperlane.xyz/relay', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    origin_chain: 'base',
    tx_hash: '0xabc123...',
  }),
});
const { messages } = await response.json();

import requests

response = requests.post('https://relay-api.hyperlane.xyz/relay', json={
    'origin_chain': 'base',
    'tx_hash': '0xabc123...',
})
messages = response.json()['messages']

{
  "messages": [
    {
      "message_id": "a1b2c3d4e5f6...",
      "origin": 8453,
      "destination": 1,
      "nonce": 42
    }
  ]
}

{
  "messages": []
}

"origin_chain cannot be empty"

"Transaction already submitted recently"

"Request timeout"

Errors

Status	Reason	Description
`400 Bad Request`	`invalid_request`	`origin_chain` or `tx_hash` is empty, exceeds max length, or the chain is not found.
`400 Bad Request`	`message_not_whitelisted`	A message in the transaction does not match the relayer’s whitelist.
`400 Bad Request`	`message_blacklisted`	A message in the transaction matches the relayer’s blacklist.
`400 Bad Request`	`unsupported_destination`	The message destination chain is not configured on this relayer.
`400 Bad Request`	`too_many_messages`	The transaction contains more than 10 Hyperlane messages.
`408 Request Timeout`	`timeout`	The transaction receipt was not found within 10 seconds. Retry after the transaction is confirmed.
`429 Too Many Requests`	`rate_limited`	The global rate limit has been exceeded. Retry after a short backoff.
`429 Too Many Requests`	`duplicate_tx`	The same `(origin_chain, tx_hash)` was already submitted within the last 5 minutes.
`503 Service Unavailable`	`cache_full`	The deduplication cache is full. Retry shortly.
`500 Internal Server Error`	—	An internal error occurred. The request can be retried safely unless messages were partially enqueued.

Eligibility

Currently only CCTP V2 messages on EVM chains are eligible. A transaction qualifies when the number of MessageSent events from Circle’s MessageTransmitter V2 contract equals the number of Hyperlane Dispatch events. Messages that do not meet this criterion are silently omitted from the response rather than causing an error.

Deduplication

The relayer maintains a 5-minute deduplication window per (origin_chain, tx_hash) pair. Submitting the same transaction a second time within this window returns 429 Too Many Requests. After 5 minutes the same hash can be resubmitted. If the request fails with a non-2xx status the reservation is released immediately so the client can retry right away.

Health Check

A GET /relay request returns 200 OK with body up and can be used as a liveness probe.

curl http://localhost:9090/relay
# up

Relayer HTTP API List Operations

⌘I

Introduction

Key Management

Validators

Relayer

Agent Config

Guides

Submit Transaction for Relay

Errors

Eligibility

Deduplication

Health Check

​Errors

​Eligibility

​Deduplication

​Health Check

Errors

Eligibility

Deduplication

Health Check