App Kits - Arc Docs

App Kits is a suite of SDKs for composing multichain payment and liquidity flows without orchestrating separate, low-level protocol integrations for each blockchain or use case. The App Kit SDK is the all-in-one core package. Install it to access every capability — Send, Bridge, Swap, and Unified Balance — behind one type-safe interface. Or, you can install Bridge Kit, Swap Kit, or Unified Balance Kit separately.

Quick install

To get started quickly, install the App Kit SDK and the Viem adapter:

npm install @circle-fin/app-kit @circle-fin/adapter-viem-v2 viem

Need a different adapter or individual kits? See the full installation guide.

Core capabilities

Combine and use any of the App Kit SDK’s built-in core capabilities in your app. Bridge, Swap, and Unified Balance are also available as individual kits.

Bridge

Transfer USDC across blockchains.

Swap

Exchange one token for another on the same blockchain or across blockchains.

Send

Transfer tokens between wallets on the same blockchain.

Unified Balance

Create a chain-abstracted balance and spend it instantly.

Key benefits

Simple setup: Get up and running with minimal configuration and a few lines of code.
Application monetization: Collect a custom fee from end users without writing new code.
Flexible configurations: Specify custom RPC endpoints and wallet clients.
Broad compatibility: Works with Viem, Ethers, Solana, and Circle Wallets, integrating smoothly with existing developer workflows.
Protocol abstraction: Build against a single interface over underlying protocols such as Gateway and CCTP.
Composable workflows: Combine multiple capabilities in one product flow without stitching together separate protocol integrations.

Quick look

The following examples show how each capability can be integrated with a single method call.

Bridge
Swap
Unified Balance
Send

TypeScript

// Transfer 1.00 USDC from Ethereum to Arc
const result = await kit.bridge({
  from: { adapter: viemAdapter, chain: "Ethereum_Sepolia" },
  to: { adapter: viemAdapter, chain: "Arc_Testnet" },
  amount: "1.00",
});

Ready to start bridging? Follow the Bridge tokens across blockchains quickstart.

TypeScript

// Swap 1.00 USDC for EURC on Arc Testnet
const result = await kit.swap({
  from: { adapter: viemAdapter, chain: "Arc_Testnet" },
  tokenIn: "USDC",
  tokenOut: "EURC",
  amountIn: "1.00",
  config: {
    kitKey: process.env.KIT_KEY as string, // Your kit key from the Circle Console
  },
});

Ready to start swapping? Follow the Swap tokens on a blockchain quickstart.

TypeScript

// Deposit 1.00 USDC into the Unified Balance from Base
const depositBase = await kit.unifiedBalance.deposit({
  from: { adapter: viemAdapter, chain: "Base_Sepolia" },
  amount: "1.00",
  token: "USDC",
});
// Deposit 1.00 USDC into the Unified Balance from Arbitrum
const depositArb = await kit.unifiedBalance.deposit({
  from: { adapter: viemAdapter, chain: "Arbitrum_Sepolia" },
  amount: "1.00",
  token: "USDC",
});
// Spend 1.50 USDC from the Unified Balance on Arc
const spendResult = await kit.unifiedBalance.spend({
  from: { adapter: viemAdapter },
  amountIn: "1.50",
  to: {
    adapter: viemAdapter,
    chain: "Arc_Testnet",
    recipientAddress: "0xRecipientAddress",
  },
});

Ready to start using a Unified Balance? Follow the quickstarts:

TypeScript

// Send 1.00 USDC from one wallet to another on Arc Testnet
const result = await kit.send({
  from: { adapter: viemAdapter, chain: "Arc_Testnet" },
  to: "RECIPIENT_ADDRESS",
  amount: "1.00",
  token: "USDC",
});

Ready to start sending tokens? Follow the Send tokens across wallets quickstart.

Want to combine capabilities? Follow the Swap tokens across chains quickstart to swap and bridge tokens in the same flow.

​Quick install

​Core capabilities

Bridge

Swap

Send

Unified Balance

​Key benefits

​Quick look

Quick install

Core capabilities

Key benefits

Quick look