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

# Quickstart: Borrow USDC against cirBTC collateral

> Provision a wallet, discover an available lending market, borrow USDC against cirBTC collateral, and confirm the funds landed in your Mint balance.

To borrow USDC against cirBTC, you provision a wallet, discover a lending
market, and originate a borrow. For the underlying concepts, see
[How Digital Asset-Backed Borrowing works](/circle-mint/concepts/digital-asset-backed-borrowing).

## Prerequisites

Before you begin, ensure that you've:

* [Contacted Circle](https://www.circle.com/mint-contact) to enable Digital
  Asset-Backed Borrowing on your Circle Mint account.
* [Set up your Mint account](/circle-mint/quickstarts/getting-started).
* Funded your Mint balance with sufficient cirBTC to serve as collateral for the
  borrow amount you plan to request.
* Registered a WebAuthn passkey on the device that will act as the recovery
  owner of your wallet.

## Step 1. Discover available markets

Call
[`GET /v1/borrow/markets`](/api-reference/circle-mint/digital-asset-backed-borrowing/list-borrow-markets)
to list the lending markets Circle has approved for your entity. Each market
entry describes the collateral asset, the borrow asset, current rates, and the
LTV caps you must respect when originating a borrow.

Request:

```bash theme={null}
curl https://api-sandbox.circle.com/v1/borrow/markets \
  -H "Authorization: Bearer $API_KEY"
```

Response:

```json theme={null}
{
  "data": [
    {
      "id": "d24e8f01-2345-6789-abcd-ef0123456789",
      "protocol": "morpho",
      "displayName": "cirBTC / USDC (Morpho Blue)",
      "marketId": "0x3a85e6f1c2d3b4a596877869504132e1d0c9b8a7766554433221100ffeeddccbb",
      "lltv": "0.86",
      "maxOriginationLtv": "0.80",
      "borrowApy": "0.0542",
      "borrowAsset": "USD",
      "collateralAsset": "CIRBTC",
      "oraclePrice": "50000.00",
      "marketDataUpdateDate": "2026-06-24T12:00:00.000Z",
      "isActive": true
    }
  ]
}
```

Save the `marketId` from the response. You pass it to the borrow endpoint in
Step 3.

Before proceeding, confirm that `isActive` is `true` and estimate the LTV of
your planned borrow using `oraclePrice`. Keep the ratio below
`maxOriginationLtv` or Circle rejects the origination.

## Step 2. Provision your wallet

Circle mints an ECDSA co-signer key, configures a two-owner MSCA on Arc
(Circle's co-signer plus your passkey), and deploys the account onchain. This
step is asynchronous.

### Step 2.1. Submit the wallet creation request

From your registered passkey, capture the P-256 public key and the WebAuthn
credential identifier as hex strings. Call
[`POST /v1/borrow/wallets`](/api-reference/circle-mint/digital-asset-backed-borrowing/create-borrow-wallet)
with both.

Request:

```bash theme={null}
curl -X POST https://api-sandbox.circle.com/v1/borrow/wallets \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "idempotencyKey": "b3d9d2d5-4c12-4946-a09d-953e82fae2b0",
    "ownerKey": "0x04b0a1c2d3e4f5061728394a5b6c7d8e9f00112233445566778899aabbccddeeff",
    "credentialId": "a1b2c3d4e5f60718"
  }'
```

The endpoint returns a `wallet_setup` job:

```json theme={null}
{
  "data": {
    "id": "1a2b3c4d-5e6f-7089-abcd-ef1234567890",
    "jobType": "wallet_setup",
    "status": "received",
    "createDate": "2026-06-20T14:10:00.000Z",
    "updateDate": "2026-06-20T14:10:00.000Z"
  }
}
```

Save the job `id` for the next substep.

### Step 2.2. Poll the job until it completes

Call
[`GET /v1/borrow/jobs/{id}`](/api-reference/circle-mint/digital-asset-backed-borrowing/get-borrow-job)
and poll until `status` reaches `completed`.

Request:

```bash theme={null}
curl https://api-sandbox.circle.com/v1/borrow/jobs/1a2b3c4d-5e6f-7089-abcd-ef1234567890 \
  -H "Authorization: Bearer $API_KEY"
```

Response (once the job completes):

```json theme={null}
{
  "data": {
    "id": "1a2b3c4d-5e6f-7089-abcd-ef1234567890",
    "jobType": "wallet_setup",
    "status": "completed",
    "txHash": "0x1a2b3c4d5e6f70819293a4b5c6d7e8f90a1b2c3d4e5f60718293a4b5c6d7e8f9",
    "createDate": "2026-06-20T14:10:00.000Z",
    "updateDate": "2026-06-20T14:12:00.000Z"
  }
}
```

### Step 2.3. Fetch your new wallet

Once the job completes, call
[`GET /v1/borrow/wallets`](/api-reference/circle-mint/digital-asset-backed-borrowing/list-borrow-wallets)
to retrieve the MSCA address and the per-asset deposit addresses.

Request:

```bash theme={null}
curl https://api-sandbox.circle.com/v1/borrow/wallets \
  -H "Authorization: Bearer $API_KEY"
```

Response:

```json theme={null}
{
  "data": [
    {
      "id": "9c1b2a3d-4e5f-6071-8293-a4b5c6d7e8f9",
      "walletAddress": "0x742d35Cc6634C0532925a3b844Bc9e7595f9f68C",
      "owners": [
        {
          "id": "1f2e3d4c-5b6a-7980-1234-56789abcdef0",
          "ownerType": "passkey",
          "publicKey": "0x04b0a1c2d3e4f5061728394a5b6c7d8e9f00112233445566778899aabbccddeeff",
          "credentialId": "a1b2c3d4e5f60718",
          "status": "active",
          "addedDate": "2026-06-20T14:10:00.000Z"
        }
      ],
      "depositAddresses": {
        "USDC": "0x5a0b4a11d3f9b2c1e8a7d6c5b4a39281f0e1d2c3",
        "cirBTC": "0xbb81dcaf9e7a6b5c4d3e2f1908172635445362718"
      },
      "createDate": "2026-06-20T14:10:00.000Z"
    }
  ]
}
```

## Step 3. Originate a borrow

Call
[`POST /v1/borrow/loans`](/api-reference/circle-mint/digital-asset-backed-borrowing/create-borrow-loan)
with the `marketId` from Step 1, the amount of cirBTC you want to post as
collateral, and the amount of USDC you want to borrow. The example below borrows
3,000 USDC against 0.2 cirBTC (worth 10,000 USDC at the market's oracle price of
50,000).

Request:

```bash theme={null}
curl -X POST https://api-sandbox.circle.com/v1/borrow/loans \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "idempotencyKey": "ba943ff1-ca16-49b2-ba55-1057e70ca5c7",
    "protocol": "morpho",
    "marketId": "0x3a85e6f1c2d3b4a596877869504132e1d0c9b8a7766554433221100ffeeddccbb",
    "collateralAmount": "20000000",
    "borrowAmount": "3000000000"
  }'
```

<Note>
  Request amounts use raw `uint256` base units (decimal-integer string, no
  fractional part). Response amounts, in later steps, use the asset's natural
  unit. In the example above, `20000000` represents `0.2` cirBTC (cirBTC uses 8
  decimals), and `3000000000` represents `3,000` USDC (USDC uses 6 decimals).
</Note>

Response:

```json theme={null}
{
  "data": {
    "id": "b3d9d2d5-4c12-4946-a09d-953e82fae2b0",
    "jobType": "borrow",
    "status": "received",
    "amount": "3000.00",
    "asset": "USD",
    "collateralAmount": "0.2",
    "collateralAsset": "CIRBTC",
    "createDate": "2026-06-20T14:20:00.000Z",
    "updateDate": "2026-06-20T14:20:00.000Z"
  }
}
```

Save the job `id` for the next step.

## Step 4. Poll the job to completion

Circle builds, signs, and submits the onchain UserOperation for the borrow. The
job progresses through `submitted` and `confirmed` to `completed`. Poll
[`GET /v1/borrow/jobs/{id}`](/api-reference/circle-mint/digital-asset-backed-borrowing/get-borrow-job)
until you see the terminal state.

Response (once the job completes):

```json theme={null}
{
  "data": {
    "id": "b3d9d2d5-4c12-4946-a09d-953e82fae2b0",
    "jobType": "borrow",
    "status": "completed",
    "amount": "3000.00",
    "asset": "USD",
    "collateralAmount": "0.2",
    "collateralAsset": "CIRBTC",
    "toAddress": "0x5a0b4a11d3f9b2c1e8a7d6c5b4a39281f0e1d2c3",
    "loanId": "fc988ed5-c129-4f70-a064-e5beb7eb8e32",
    "oraclePrice": "50000.00",
    "userOpHash": "0x9f8e7d6c5b4a39281f0e1d2c3b4a5968778695a4b3c2d1e0f9a8b7c6d5e4f3a2",
    "txHash": "0x1a2b3c4d5e6f70819293a4b5c6d7e8f90a1b2c3d4e5f60718293a4b5c6d7e8f9",
    "createDate": "2026-06-20T14:20:00.000Z",
    "updateDate": "2026-06-20T14:22:00.000Z"
  }
}
```

Once `status` is `completed`, the job's `loanId` identifies your new loan. The
borrowed USDC has been credited to your Mint balance.

## Step 5. Confirm the loan and USDC receipt

Fetch the loan to inspect the position.

Request:

```bash theme={null}
curl https://api-sandbox.circle.com/v1/borrow/loans/fc988ed5-c129-4f70-a064-e5beb7eb8e32 \
  -H "Authorization: Bearer $API_KEY"
```

Response:

```json theme={null}
{
  "data": {
    "id": "fc988ed5-c129-4f70-a064-e5beb7eb8e32",
    "protocol": "morpho",
    "marketId": "0x3a85e6f1c2d3b4a596877869504132e1d0c9b8a7766554433221100ffeeddccbb",
    "walletAddress": "0x742d35Cc6634C0532925a3b844Bc9e7595f9f68C",
    "borrowAsset": "USD",
    "collateralAsset": "CIRBTC",
    "collateralAmount": "0.2",
    "debtAmount": "3000.00",
    "oraclePrice": "50000.00",
    "ltv": "0.30",
    "healthFactor": "2.85",
    "borrowApy": "0.0542",
    "status": "active",
    "createDate": "2026-06-20T14:22:00.000Z",
    "updateDate": "2026-06-21T09:00:00.000Z"
  }
}
```

The loan is `active`, `collateralAmount` reflects the cirBTC you posted,
`debtAmount` reflects the USDC you borrowed, and `healthFactor` is comfortably
higher than `1.0`. Confirm the borrowed USDC has landed in your Circle Mint
balance by calling `GET /v1/businessAccount/balances`. The `available` balance
should reflect the credited amount.