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

# Quickstart: Originate a loan

> Use the App Kit SDK to borrow USDC against cirBTC collateral on Arc

Borrow USDC against cirBTC collateral on Arc Testnet. This quickstart uses the
Viem adapter.

## Prerequisites

Before you begin, ensure that you've:

* Installed [Node.js v22+](https://nodejs.org/).
* Created an EVM wallet using a wallet provider such as MetaMask and added Arc
  Testnet as a network.
* Funded your wallet with testnet cirBTC for collateral and testnet USDC for gas
  on Arc Testnet from the [Circle Faucet](https://faucet.circle.com/).

## Step 1. Set up the project

### 1.1. Create the project and install dependencies

Create a project directory, initialize a Node.js project with an ES module type
and run scripts, then install runtime and dev dependencies:

```bash Shell theme={null}
mkdir app-kit-borrow-originate
cd app-kit-borrow-originate
npm init -y
npm pkg set type=module
npm pkg set scripts.explore-markets="tsx --env-file=.env explore-markets.ts"
npm pkg set scripts.borrow="tsx --env-file=.env borrow.ts"
npm install @circle-fin/app-kit @circle-fin/adapter-viem-v2 viem tsx
npm install --save-dev typescript @types/node
```

<Tip>
  Only need Borrow and want a lighter install than the full App Kit? Install the
  standalone package instead: `@circle-fin/borrow-kit`
</Tip>

### 1.2. Configure TypeScript (optional)

<Info>
  This step is optional. It helps prevent missing types in your IDE or editor.
</Info>

Create a `tsconfig.json` file configured for ESM and Node:

```bash Shell theme={null}
cat <<'EOF' > tsconfig.json
{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "types": ["node"]
  }
}
EOF
```

### 1.3. Set environment variables

Create a `.env` file in the project directory and add it to your `.gitignore`.
Open `.env` in your editor and add your wallet's private key. Replace
`YOUR_PRIVATE_KEY` with the private key of the wallet you funded with cirBTC:

```text .env theme={null}
PRIVATE_KEY=YOUR_PRIVATE_KEY
```

<Tip>
  Edit `.env` files in your IDE or editor so credentials are not leaked to your
  shell history.
</Tip>

## Step 2. Explore available markets

`kit.borrow.exploreMarkets` returns the markets available on a blockchain along
with each market's collateral and loan tokens, borrow APY, LLTV, and liquidity.
Use it to pick a market to borrow from.

### 2.1. Create the discovery script

Create an `explore-markets.ts` file:

```typescript explore-markets.ts theme={null}
import { AppKit } from "@circle-fin/app-kit";

const kit = new AppKit();

async function main() {
  const { markets } = await kit.borrow.exploreMarkets({
    chain: "Arc_Testnet",
    sortBy: "borrowApy",
  });

  console.log(`Found ${markets.length} markets on this page`);
  console.dir(markets, { depth: null, colors: true });
}

void main();
```

### 2.2. Run the discovery script

In your terminal, run:

```bash Shell theme={null}
npm run explore-markets
```

You'll see one or more markets with their `marketId`, `borrowApy`, `lltv`, and
`liquidity` fields. Copy a `marketId` for the next step.

To walk every matching market without paging through the results yourself, use
`kit.borrow.exploreMarketsIterator`. It accepts the same filters as
`exploreMarkets` and yields one market at a time:

```typescript TypeScript theme={null}
for await (const market of kit.borrow.exploreMarketsIterator({
  chain: "Arc_Testnet",
  sortBy: "borrowApy",
})) {
  console.log(market.marketId, market.borrowApy);
}
```

## Step 3. Open the loan

<Info>
  Each market allows one open loan per wallet at a time. If a loan is already open
  for the wallet in that market, opening a new one raises
  [`BORROW_LOAN_ALREADY_EXISTS`](/app-kit/references/borrow-error-handling#input-errors)
  with the existing `loanId` in the message.
</Info>

### 3.1. Create the borrow script

Create a `borrow.ts` file. Replace `YOUR_SELECTED_MARKET_ID` with the market ID
you copied. This script borrows 1,000 USDC against cirBTC:

```typescript borrow.ts theme={null}
import { AppKit } from "@circle-fin/app-kit";
import { createViemAdapterFromPrivateKey } from "@circle-fin/adapter-viem-v2/next";

const kit = new AppKit();
const marketId = "YOUR_SELECTED_MARKET_ID";
const borrowAmount = "1000.0";

const adapter = createViemAdapterFromPrivateKey({
  privateKey: process.env.PRIVATE_KEY as `0x${string}`,
});

async function main() {
  const result = await kit.borrow.borrow({
    from: { adapter, chain: "Arc_Testnet" },
    marketId,
    borrowAmount,
  });

  console.dir(result, { depth: null, colors: true });
}

void main();
```

### 3.2. Run the borrow script

In your terminal, run:

```bash Shell theme={null}
npm run borrow
```

On confirmation, the result includes the new `loanId`, the `amountBorrowed`, and
a `txHash`.

## Step 4. Manage the loan

Use the loan's `loanId` to keep operating on it over time:

* [Add collateral or borrow more](/app-kit/howtos/borrow/add-collateral-or-borrow-more)
  against the loan.
* [Pay down the loan](/app-kit/howtos/borrow/pay-down-a-loan) with a partial
  repayment, full close, or collateral withdrawal.
* [Monitor the loan](/app-kit/howtos/borrow/monitor-a-loan) by reading its
  position or registering a webhook for health updates.