FAQ

Cross-Chain Transfer Protocol (CCTP) is a permissionless on-chain utility that can burn native USDC on a source chain and mint native USDC of the same amount on a destination chain. Developers can embed CCTP into their apps to provide users with the most capital-efficient way to transfer USDC across chains, unifying liquidity across the ecosystem and simplifying user experience.

What is Cross-Chain Transfer Protocol (CCTP)?

CCTP is a permissionless on-chain utility that enables the flow of USDC across chains through native burning and minting. With CCTP, USDC is effectively "teleported" from one blockchain to another.

Who is CCTP designed for?

CCTP was created for for third-party developers, serving as a permissionless infrastructure they could build on top of or integrate into their existing apps/dApps, wallets, and bridges.

Does CCTP require signing up with Circle?

No. CCTP is a permissionless on-chain utility for third-party developers.

When will CCTP be available on additional chains?

CCTP is available now on mainnet for Ethereum and Avalanche. Expansion to additional chains is expected throughout 2023. Developers can access our developer docs to begin building on CCTP.

Can’t I use a Circle Account or Core API to move USDC across chains? What about a centralized exchange?

Yes, Circle Account and Core API are capable of moving USDC natively across chains. However, those commercial products are only available to qualified businesses approved by Circle.

Centralized exchanges typically hold various native forms of USDC liquidity on their platforms. Users with an account at a centralized exchange can deposit USDC (native to a given chain) into their exchange wallet, and then withdraw USDC (native to a different chain) to their external wallet.

In contrast, CCTP is permissionless. This means it is accessible to any third-party developer to integrate into their app(s), and does not require signing up for an account. Users can move USDC through a CCTP-enabled app to any supported blockchain at any time. Developers can also compose new on-chain experiences on top of CCTP within their apps.

How is CCTP different from cross-chain liquidity pool solutions?

CCTP is more capital-efficient than cross-chain liquidity pool solutions because it avoids tying up liquidity in pools. Also, it does not require additional fees to incentivize liquidity providers.

How does a given quantity of USDC burned on the source chain become successfully minted on the destination chain?

All burns of USDC emit an event on the source chain, which is automatically observed by Circle’s attestation service. The app facilitating the burn of USDC is responsible for fetching the signed attestation from Circle, which then enables CCTP to mint USDC on the destination chain.

Have the CCTP smart contracts undergone security audits?

Yes. Please see our third-party audit documentation conducted by ChainSecurity (view PDF) and Halborn (view PDF) for more details.

What happens if Circle’s attestation service is unresponsive?

While Circle’s attestation service becoming unavailable would temporarily preclude new burn messages from being signed, we anticipate the same robust uptime and availability currently delivered by our existing minting and redemption services.

Does Circle have access to or store any personally identifiable information (PII) when a user sends USDC through CCTP?

No.

How does CCTP affect existing bridged versions of USDC?

CCTP has no direct impact upon existing bridged versions of USDC.

How does CCTP affect Circle’s plans to launch USDC on more blockchains?

Circle’s plans to bring USDC natively to more blockchain networks remain the same and will continue to grow. We envision CCTP establishing USDC as a universal liquidity layer for Web3 that is accessible to all.