> ## Documentation Index
> Fetch the complete documentation index at: https://docs.flarehq.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Bridge USDC to Arc Testnet Using Circle CCTP Protocol

> Transfer native USDC from Ethereum, Arbitrum, or Solana into Arc testnet with 1:1 capital efficiency and no slippage using Circle CCTP.

All FlareHQ payment features — hosted checkout, streaming payments, escrow — operate on Arc testnet (chain ID `5042002`). If your USDC is sitting on Ethereum, Arbitrum, or Solana, you need to bridge it across before you can use it. FlareHQ's CCTP bridge uses Circle's Cross-Chain Transfer Protocol to move **native USDC** — not a wrapped token — with 1:1 capital efficiency and no slippage.

## Why Native USDC Matters

Circle's CCTP burns USDC on the source chain and mints an equivalent amount on the destination chain. Unlike liquidity-pool bridges, there is no wrapped token, no price deviation, and no bridge liquidity ceiling. Every 1 USDC you send in is exactly 1 USDC on Arc when it arrives.

## Supported Chains

<CardGroup cols={3}>
  <Card title="Ethereum" icon="ethereum">
    Mainnet and Sepolia testnet supported as source chains.
  </Card>

  <Card title="Arbitrum" icon="circle-nodes">
    Arbitrum One and Arbitrum Sepolia supported as source chains.
  </Card>

  <Card title="Solana" icon="sun">
    Solana mainnet and devnet supported as source chains.
  </Card>
</CardGroup>

The destination chain is always `ARC-TESTNET` (chain ID `5042002`).

## Initiating a Bridge Transfer

<Steps>
  ### Ensure You Have a FlareHQ Wallet

  The CCTP bridge routes funds from your FlareHQ-created wallet on the source chain. Bring-your-own (external) wallets cannot be bridged automatically — the transfer must originate from a wallet provisioned at FlareHQ sign-up.

  <Note>
    If you do not yet have test USDC on the source chain, visit the Circle faucet at [faucet.circle.com](https://faucet.circle.com) and select **ARC-TESTNET** to receive test USDC directly on Arc, or select your preferred source chain if you want to test the bridge flow end-to-end.
  </Note>

  ### Start the Transfer

  Submit the source chain, destination chain, amount, and the Arc wallet address that should receive the bridged USDC.

  ```bash theme={null}
  curl -X POST https://flarehq.xyz/api/cctp/transfer \
    -H "Authorization: Bearer fhq_sec_..." \
    -H "Content-Type: application/json" \
    -d '{
      "sourceChain": "ETH-SEPOLIA",
      "destinationChain": "ARC-TESTNET",
      "amount": "100.00",
      "recipientAddress": "0xYourArcWalletAddress"
    }'
  ```

  ### Poll for Completion

  The bridge runs asynchronously. Use the `id` from the response to poll the status endpoint until `status` reaches `"completed"`.

  ```bash theme={null}
  curl "https://flarehq.xyz/api/cctp/transfer/status?id={transferId}" \
    -H "Authorization: Bearer fhq_sec_..."
  ```
</Steps>

## Request Parameters

<ParamField body="sourceChain" type="string" required>
  Source chain identifier. Accepted values: `"ETH-MAINNET"`, `"ETH-SEPOLIA"`, `"ARB-MAINNET"`, `"ARB-SEPOLIA"`, `"SOL-MAINNET"`, `"SOL-DEVNET"`.
</ParamField>

<ParamField body="destinationChain" type="string" required>
  Destination chain. Must be `"ARC-TESTNET"`.
</ParamField>

<ParamField body="amount" type="string" required>
  USDC amount to bridge, as a decimal string, e.g. `"100.00"`.
</ParamField>

<ParamField body="recipientAddress" type="string" required>
  The 0x destination wallet address on Arc testnet that will receive the bridged USDC.
</ParamField>

## Response Fields

<ResponseField name="success" type="boolean">
  `true` when the bridge transfer was initiated successfully.
</ResponseField>

<ResponseField name="status" type="string">
  Always `"pending"` on the initial response. Poll the status endpoint to track progress.
</ResponseField>

<ResponseField name="id" type="string">
  Unique transfer identifier. Use this with `GET /api/cctp/transfer/status?id=...` to check progress.
</ResponseField>

<ResponseField name="message" type="string">
  Human-readable instruction pointing to the status endpoint.
</ResponseField>

### Example Response

```json theme={null}
{
  "success": true,
  "status": "pending",
  "id": "cctp_ref_8x2nq7w4",
  "message": "Bridge started — poll /api/cctp/transfer/status?id=cctp_ref_8x2nq7w4 to check progress."
}
```

## Checking Transfer Status

```bash theme={null}
curl "https://flarehq.xyz/api/cctp/transfer/status?id=cctp_ref_8x2nq7w4" \
  -H "Authorization: Bearer fhq_sec_..."
```

| Status      | Meaning                                                     |
| ----------- | ----------------------------------------------------------- |
| `pending`   | Transfer initiated; source-chain burn transaction submitted |
| `attesting` | Circle's attestation service is signing the burn proof      |
| `minting`   | Mint transaction submitted on Arc testnet                   |
| `completed` | USDC has arrived in the recipient's Arc wallet              |
| `failed`    | Transfer failed; check the `error` field for details        |

## Settlement Time

EVM source chains (Ethereum, Arbitrum) typically settle in **\~2 minutes**. This covers:

1. Source-chain finality for the burn transaction (\~1 minute on Arbitrum, up to \~15 blocks on Ethereum)
2. Circle attestation service signing the proof (\~30 seconds)
3. Arc testnet mint transaction confirmation (\~15 seconds)

Solana transfers may take slightly longer due to attestation differences.

## Getting Test USDC

You do not need mainnet USDC to test with FlareHQ. Circle provides a testnet faucet:

1. Go to [faucet.circle.com](https://faucet.circle.com).
2. Select **ARC-TESTNET** from the chain dropdown.
3. Paste your Arc wallet address and click **Request Funds**.
4. Test USDC arrives within \~30 seconds — no bridging required.

If you specifically want to test the full bridge flow, select **ETH-SEPOLIA** or **ARB-SEPOLIA** in the faucet, request test USDC there, then bridge it into Arc using the endpoint above.

## Listing Supported Chains

To programmatically fetch the current list of supported source and destination chains:

```bash theme={null}
curl https://flarehq.xyz/api/cctp/transfer \
  -H "Authorization: Bearer fhq_sec_..."
```

```json theme={null}
{
  "success": true,
  "sourceChains": [
    { "id": "ETH-SEPOLIA", "name": "Ethereum Sepolia" },
    { "id": "ARB-SEPOLIA", "name": "Arbitrum Sepolia" },
    { "id": "SOL-DEVNET",  "name": "Solana Devnet" }
  ],
  "destinationChains": [
    { "id": "ARC-TESTNET", "name": "Arc Testnet", "chainId": 5042002 }
  ]
}
```

<Warning>
  **Bridging is one-directional in this guide.** This tutorial covers inbound transfers to Arc testnet only. To move USDC back out of Arc to another chain, initiate a separate CCTP transfer with Arc as the source and your preferred chain as the destination. Funds bridged into Arc cannot be recovered by reversing the same transfer — you must start a new outbound transfer.
</Warning>