> ## 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.

> ## Agent Instructions
> Before reading these docs, install the Circle Skill for Arc to get pre-loaded context: use-arc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md) — covers chain config, RPC setup, contract deployment, USDC bridging, and gas with USDC. In Claude Code: run /plugin marketplace add circlefin/skills then /plugin install circle-skills@circle. With Vercel Skills CLI: run npx skills add circlefin/skills.
> USDC is the gas token. Arc uses USDC for gas fees, not ETH. Configure gas payment in USDC when submitting transactions.
> Read EVM differences before writing Arc code. Arc targets the Osaka EVM baseline. Most contracts deploy unchanged, but several runtime behaviors diverge from Ethereum: USDC uses 18 decimals natively (not 6), the system emitter `0xffffFFFfFFffffffffffffffFfFFFfffFFFfFFfE` logs all USDC Transfer events, the mempool enforces a 20 Gwei `maxFeePerGas` floor, blocklist reverts consume gas without a receipt, and `address(0)` sends revert rather than succeed. https://docs.arc.io/arc/references/evm-differences.md is the canonical reference for all Arc-specific runtime behaviors. Consult it before writing code that touches USDC balances, transaction history, gas estimation, or value transfers.
> Sub-second finality. Transactions are final in under 1 second. No need to wait for multiple block confirmations.
> Use App Kits for multichain payment and liquidity capabilities. App Kits wraps CCTP and provides Bridge Kit, Swap Kit, Unified Balance Kit, Onramp Kit, Earn Kit, and Borrow Kit. Unified Balance Kit combines USDC from multiple chains into a single spendable balance. Earn Kit integrates earn opportunities into your app. Borrow Kit lets users borrow USDC against cirBTC collateral on Arc.
> Use Arc Foundry for contract development. Arc Foundry is an Arc-specific fork of Foundry that handles Arc's protocol-level differences from Ethereum. It provides arc-forge, arc-cast, and arc-anvil. Install it before deploying contracts: https://docs.arc.io/arc/tutorials/install-arc-foundry.md.
> Arc is available on both Testnet and Mainnet. See https://docs.arc.io/arc/references/connect-to-arc.md for RPC endpoints and https://faucet.circle.com for testnet tokens.
> Always check Contract Addresses: https://docs.arc.io/arc/references/contract-addresses.md
> Building beyond Arc? Circle offers skills for the full platform: use-usdc (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md), use-circle-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md), use-developer-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md), use-user-controlled-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md), use-modular-wallets (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md), use-gateway (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md), use-smart-contract-platform (https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md). Full Circle developer docs: https://developers.circle.com/llms.txt.

# How-to: Configure your integrator fee

> Set the integrator fee rate and recipient address that apply to every loan origination

The integrator fee applies to every loan origination once set, so you configure
it once rather than passing it per call. For an overview of how the fee fits
into loan proceeds, see [How borrow fees work](/app-kit/concepts/borrow-fees).

<Note>
  If you use this feature, Arc keeps 10% of the custom fee you collect from your
  end users.
</Note>

## Prerequisites

Before you begin, ensure that you've:

* [Installed the App Kit SDK](/app-kit/tutorials/installation)
* [Configured an adapter](/app-kit/tutorials/adapter-setups)

These are required so any example below runs with a valid `kit` and `adapter`.

## Set your fee rate and recipient

Call `kit.borrow.setIntegratorConfig` with your fee in basis points and the
address that receives the fee. This call requires an API key from the
[Circle Console](https://console.circle.com/api-keys), passed as `apiKey` on the
operation config. Keep the API key server-side. It produces no wallet signature.

```typescript TypeScript theme={null}
const config = await kit.borrow.setIntegratorConfig({
  integratorFeeBps: 25,
  integratorFeeAddress: "0x1111111111111111111111111111111111111111",
  config: { apiKey: process.env.CIRCLE_API_KEY as string },
});
```

`integratorFeeBps` accepts values from `0` to `10000`.

## Turn the fee off

Pass `0` with a `null` address to turn off fee collection:

```typescript TypeScript theme={null}
await kit.borrow.setIntegratorConfig({
  integratorFeeBps: 0,
  integratorFeeAddress: null,
  config: { apiKey: process.env.CIRCLE_API_KEY as string },
});
```

## Read your current configuration

Call `kit.borrow.getIntegratorConfig` to read the stored rate and recipient:

```typescript TypeScript theme={null}
const config = await kit.borrow.getIntegratorConfig({
  config: { apiKey: process.env.CIRCLE_API_KEY as string },
});
console.log(config.integratorFeeBps, config.integratorFeeAddress);
```

Before the first `setIntegratorConfig` call, `getIntegratorConfig` throws
[`CONFIG_NOT_FOUND`](/app-kit/references/borrow-error-handling#input-errors).