> ## Documentation Index
> Fetch the complete documentation index at: https://a-identity.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Circle CCTP

> Native USDC across chains by burn-and-mint — never wrapped.

**CCTP** (Cross-Chain Transfer Protocol) is Circle's canonical way to move USDC
between chains: USDC is **burned** on the source chain and **minted natively** on the
destination — never a wrapped or bridged variant. A-Identity drives it with Circle's
Bridge Kit (CCTPv2), so an agent's dollars can leave Arc and arrive as real USDC on
another chain.

This is the second cross-chain rail alongside [Circle Gateway](/chains/gateway). They
solve related problems differently: Gateway moves a **unified balance** via the
Forwarding Service; CCTP is the **burn-and-mint** primitive underneath native USDC
liquidity.

## The burn-and-mint lifecycle

<Steps>
  <Step title="approve">
    The bridge is approved to spend the USDC being moved.
  </Step>

  <Step title="burn">
    USDC is burned on Arc, emitting a cross-chain message.
  </Step>

  <Step title="fetchAttestation">
    Circle attests the burn. Because Arc has instant finality, the attestation is
    reached fast.
  </Step>

  <Step title="mint">
    Native USDC is minted on the destination chain (Base Sepolia in our demo) — the
    same dollar, no wrapper.
  </Step>
</Steps>

<Note>
  Verified live on Arc testnet: a 1 USDC transfer ran the full `approve → burn →
    fetchAttestation → mint` lifecycle in about 15 seconds, each step a real transaction,
  minting native USDC on Base Sepolia — on both the local and the live production
  backend. SDK: [`@circle-fin/bridge-kit`](https://developers.circle.com/cctp).
</Note>

## Gateway vs CCTP

|                 | Circle Gateway                       | CCTP                            |
| --------------- | ------------------------------------ | ------------------------------- |
| Model           | Unified balance + Forwarding Service | Burn-and-mint                   |
| Destination gas | None (minted gaslessly)              | Standard mint on destination    |
| Best for        | Chain-abstracted spending            | Canonical native-USDC liquidity |
| In A-Identity   | `mcp/src/gateway.ts`                 | `mcp/src/cctp.ts`               |

<Warning>
  Leaving Arc, the bridged amount must exceed the CCTPv2 max fee — tiny testnet
  transfers can revert with "Max fee must be less than amount". The demo defaults to
  1 USDC.
</Warning>

<Card title="Build on Arc" icon="link" href="/chains/arc">
  Arc is the primary rail — gas in USDC, sub-second finality. CCTP and Gateway extend
  it across chains.
</Card>