> ## 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: Set slippage tolerance or stop limit on swaps

> Set a slippage or stop limit to protect against rate changes

Set a slippage tolerance or stop limit to avoid receiving less than expected on
a swap due to market fluctuations:

* A **slippage tolerance** lets you set the maximum percentage difference you're
  willing to accept between the estimated and actual swap amount, expressed in
  bps (for example, 100 bps = 1%).
* A **stop limit** lets you set the exact minimum amount you want to receive.

If both are configured, the stop limit takes precedence.

## 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 slippage tolerance

This example sets a slippage tolerance of 100 bps (1%):

```typescript TypeScript theme={null}
const output = await kit.swap({
  from: { adapter, chain: "Arc_Testnet" },
  tokenIn: "USDC",
  amountIn: "1.00",
  tokenOut: "EURC",
  config: {
    apiKey: process.env.CIRCLE_API_KEY as string, // optional — configure for production or high-volume usage
    slippageBps: 100, // Set the slippage tolerance to 100 bps
  },
});
```

With `slippageBps` as `100` as in the example, you'll receive at least 99% of
the estimated amount. Meaning if the swap rate is 1 USDC to 1 EURC, you'll
receive at least 0.99 EURC.

<Note>
  The `slippageBps` default is 300 bps. `0` represents no tolerance, which
  increases transaction failure rates.
</Note>

## Set stop limit

`stopLimit` defines the minimum amount of the token type specified in `tokenOut`
that you'll receive on a swap.

This example sets a stop limit of 0.95 EURC, meaning you won't receive any less
than that on a swap:

```typescript TypeScript theme={null}
const output = await kit.swap({
  from: { adapter, chain: "Arc_Testnet" },
  tokenIn: "USDC",
  amountIn: "1.00",
  tokenOut: "EURC",
  config: {
    apiKey: process.env.CIRCLE_API_KEY as string, // optional — configure for production or high-volume usage
    stopLimit: "0.95", // Set stop limit to 0.95 EURC
  },
});
```