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Overview

The CCTP API exposes the parts of the cross-chain flow that matter to integrators:
  • supported Circle domains and receiver addresses,
  • fast vs standard transfer fee estimates,
  • relay job lookup by source transaction hash,
  • and a manual fallback endpoint to start relay for a known source transaction.
In production, the normal relay path is event-driven:
  1. your user executes the router transaction on the source chain,
  2. 1tx receives the router bridge event through a webhook,
  3. 1tx waits for Circle attestation,
  4. 1tx redeems on the destination chain,
  5. your client polls relay status by source tx hash.

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Get CCTP Config

GET /cctp/config Returns the supported CCTP chains together with Circle domain IDs and destination receiver addresses. 
curl "https://api.1tx.fi/api/v1/cctp/config"

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Response

{
  "supportedChains": [
    {
      "chainId": 8453,
      "name": "Base Mainnet",
      "cctpDomain": 6,
      "tokenMessenger": "0x28b5a0e9C621a5BadaA536219b3a228C8168cf5d",
      "messageTransmitter": "0x81D40F21F12A8F0E3252Bccb954D722d4c464B64",
      "cctpReceiver": "0xAA4a2CFd29734dA2041a56A716e408F1A610f85E"
    },
    {
      "chainId": 42161,
      "name": "Arbitrum One",
      "cctpDomain": 3,
      "tokenMessenger": "0x28b5a0e9C621a5BadaA536219b3a228C8168cf5d",
      "messageTransmitter": "0x81D40F21F12A8F0E3252Bccb954D722d4c464B64",
      "cctpReceiver": "0xFCc3e94Eb1A6942a462Be9ADB657076AcD8954cB"
    }
  ]
}

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Get Transfer Fee

GET /cctp/fee/:sourceDomain/:destDomain Returns Circle fee estimates for both fast and standard transfer modes. 
curl "https://api.1tx.fi/api/v1/cctp/fee/6/3"

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Response

{
  "fastFeeBps": "1.3",
  "standardFeeBps": "0",
  "fastTransferEta": "~20 seconds",
  "standardTransferEta": "~15-19 minutes"
}

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Get Relay Status By Source Transaction Hash

GET /cctp/relay/tx/:sourceTxHash Look up the bridge job created for a specific source-chain router transaction. This is the primary endpoint clients should poll after submitting a cross-chain buy. 
curl "https://api.1tx.fi/api/v1/cctp/relay/tx/0xf43f4d3b56d8ca26615dcfc11c036096d3b39266e74b3151b78e2dcb5026951c"

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Response

{
  "jobId": "339f5b0b-99cb-40ba-a497-d849bec20e42",
  "status": "waiting_attestation",
  "sourceTxHash": "0xf43f4d3b56d8ca26615dcfc11c036096d3b39266e74b3151b78e2dcb5026951c",
  "sourceChainId": 8453,
  "destinationChainId": 42161,
  "senderAddress": "0x59f84af036712afe2fd0ec77f4d9a6f0a612f1fe",
  "attempts": 1,
  "createdAt": 1775742368892,
  "updatedAt": 1775742368897
}

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Status Values

StatusMeaning
pendingRelay job has been created but attestation polling has not started yet
waiting_attestationWaiting for Circle IRIS attestation
redeemingRelayer is submitting the destination-chain redeem() transaction
successDestination execution succeeded
failedRelay failed. Check error

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404 Behavior

Immediately after a source transaction confirms, this endpoint may briefly return 404 Job not found until the bridge webhook is ingested and the relay job is created. Clients should treat an early 404 as a retry signal, not as a permanent failure.

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Manual Relay Fallback

POST /cctp/relay Manually start or resume relay for a known source transaction. This is mainly useful for operator tooling, support flows, or emergency recovery when a webhook was missed. 
curl -X POST "https://api.1tx.fi/api/v1/cctp/relay" \
  -H "Content-Type: application/json" \
  -d '{
    "sourceTxHash": "0xc6ff364bc4caf71fde5bb1393d641cbe76710a214c51b95fd6fd4751f12fd8a2",
    "sourceChainId": 8453,
    "destinationChainId": 42161
  }'

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Response

{
  "jobId": "ae983759-88eb-455a-9fa5-4a7c322fbabe",
  "status": "pending",
  "sourceTxHash": "0xc6ff364bc4caf71fde5bb1393d641cbe76710a214c51b95fd6fd4751f12fd8a2"
}

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Webhook Endpoint

POST /cctp/webhooks/bridge This endpoint is used by 1tx bridge-event subscriptions to start relay jobs automatically when SwapDepositRouter emits CCTPBridgeInitiated. It is not part of the normal client integration flow, but is useful if you run your own event delivery.
  1. Call POST /transactions/buy.
  2. Execute the returned transactions on sourceChainId.
  3. Capture the source router transaction hash.
  4. Poll GET /cctp/relay/tx/:sourceTxHash until:
    • success, then use destinationTxHash for explorers/UI, or
    • failed, then surface the error to the user.