API Service Rate Limit
The CCTP API service rate limit is 35 requests per second. If you exceed 35 requests per second, the service blocks all API requests for the next 5 minutes and returns an HTTP 429 response.
CCTP provides a set of API hosts and endpoints to manage messages, attestations, and transaction details for your cross-chain USDC transfers.
| Environment | URL |
|---|---|
| Testnet | https://iris-api-sandbox.circle.com |
| Mainnet | https://iris-api.circle.com |
Select the CCTP version below for a summary of API endpoints supported by each version:
- CCTP V1
- CCTP V2
CCTP V1 endpoints allow you to fetch attestations for Standard Transfer burn events, verify public keys, and access transaction details. Below is an overview of the CCTP V1 public endpoints. Click on any endpoint for its API reference.
| Endpoint | Description | Use Case |
|---|---|---|
| GET /v1/attestations/{messageHash} | Retrieves the signed attestation for a USDC burn event on the source chain. | Certifying the burn of USDC post hard finality. Used as a signal to mint USDC on the destination chain. |
| GET /v1/publicKeys | Fetches Circle's active public keys for verifying attestation signatures. | Validating the authenticity of Circle's signed attestations. |
| GET /v1/messages/{sourceDomainId}/{transactionHash} | Provides transaction details for burn events or associated messages. | Accessing detailed information about CCTP V1 transactions. |
CCTP V2 endpoints enable advanced functionality such as fetching attestations for Standard Transfer or Fast Transfer burn events, verifying public keys across versions, accessing transaction details, querying fast transfer allowances and fees, and initiating re-attestation processes. Below is an overview of the CCTP V2 public endpoints. Click on any endpoint for its API reference.
| Endpoint | Description | Use Case |
|---|---|---|
| GET /v2/publicKeys | Returns public keys for validating attestations across both supported versions of CCTP (V1 and V2). | Retrieve public keys to verify attestation authenticity for cross-chain transactions. |
| GET /v2/messages/:sourceDomainId | Retrieves messages and attestations for a given transaction or nonce, supporting both V1 and V2 messages. | Fetch attestation status and transaction details. |
| POST /v2/reattest/:nonce | Re-attests a soft finality V2 message to achieve finality or revive expired Fast Transfer burns. | Handle edge cases requiring updated attestations or finalize transactions with stricter rules. |
| GET /v2/fastBurn/USDC/allowance | Retrieves the current USDC Fast Transfer allowance remaining. | Monitor available allowance for Fast Transfer burns in real-time. |
| GET /v2/fastBurn/USDC/fees/:sourceDomainId/:destDomainId | Returns the fees for USDC Fast Transfers between specified source and destination domains. | Calculate transaction costs before initiating a Fast Transfer. |
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