# Arc

> Arc is an open Layer-1 blockchain purpose-built for programmable money.
> USDC is the native gas token. Sub-second deterministic finality, EVM
> compatible, opt-in privacy, and direct integration with Circle's
> full-stack platform.

## Getting Started — Use the Skill First

| Product | Skill | What it covers |
|---------|-------|----------------|
| Arc | [use-arc](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md) | Chain config, RPC setup, contract deployment, USDC bridging, gas with USDC |

### Installing Circle Skills

**Claude Code:**
```
/plugin marketplace add circlefin/skills
/plugin install circle-skills@circle
```

**Vercel Skills CLI:**
```
npx skills add circlefin/skills
```

## Instructions for AI Agents

Follow these guidelines when building on Arc:

1. **USDC is the gas token.** Arc uses USDC for gas fees, not ETH. Configure gas payment in USDC when submitting transactions.

2. **EVM compatible.** Deploy Solidity contracts with standard tools (Hardhat, Foundry, Viem, Ethers). See [EVM Compatibility](https://docs.arc.network/arc/references/evm-compatibility.md) for differences.

3. **Sub-second finality.** Transactions are final in under 1 second. No need to wait for multiple block confirmations.

4. **Use App Kit for bridging and swaps.** App Kit wraps CCTP and provides Bridge, Swap, and Send capabilities. `@circle-fin/bridge-kit` is also available as a standalone package for bridging only.

5. **Testnet.** Arc is currently available on Testnet only. [Connect to Arc](https://docs.arc.network/arc/references/connect-to-arc.md) for RPC endpoints. [Faucet](https://faucet.circle.com) for testnet tokens.

6. **Always check Contract Addresses**: https://docs.arc.network/arc/references/contract-addresses.md

## Arc

- [Welcome to Arc](https://docs.arc.network/arc/concepts/welcome-to-arc.md): Architecture and core principles
- [System Overview](https://docs.arc.network/arc/concepts/system-overview.md): Consensus + execution layer architecture
- [Stable Fee Design](https://docs.arc.network/arc/concepts/stable-fee-design.md): USDC as gas, predictable fees
- [Deterministic Finality](https://docs.arc.network/arc/concepts/deterministic-finality.md): Instant, irreversible settlement
- [Opt-in Privacy](https://docs.arc.network/arc/concepts/opt-in-privacy.md): Confidential transactions with selective disclosure
- [Connect to Arc](https://docs.arc.network/arc/references/connect-to-arc.md): RPC endpoints and wallet setup
- [Contract Addresses](https://docs.arc.network/arc/references/contract-addresses.md): USDC, EURC, CCTP, Gateway addresses
- [EVM Compatibility](https://docs.arc.network/arc/references/evm-compatibility.md): Differences from standard EVM
- [Gas and Fees](https://docs.arc.network/arc/references/gas-and-fees.md): Fee model and pricing
- [Sample Applications](https://docs.arc.network/arc/references/sample-applications.md): Open source examples

## Tutorials

- [Deploy on Arc](https://docs.arc.network/arc/tutorials/deploy-on-arc.md): Deploy a Solidity contract on Arc Testnet
- [Deploy Contracts (Circle)](https://docs.arc.network/arc/tutorials/deploy-contracts.md): Deploy templates via Circle Contracts
- [Interact with Contracts](https://docs.arc.network/arc/tutorials/interact-with-contracts.md): Call contract functions
- [Monitor Contract Events](https://docs.arc.network/arc/tutorials/monitor-contract-events.md): Track onchain activity
- [Transfer USDC or EURC](https://docs.arc.network/arc/tutorials/transfer-usdc-or-eurc.md): Wallet-to-wallet transfers
- [Bridge USDC to Arc](https://docs.arc.network/arc/tutorials/bridge-usdc-to-arc.md): Bridge via CCTP with App Kit
- [Access USDC Crosschain](https://docs.arc.network/arc/tutorials/access-usdc-crosschain.md): Gateway unified balance on Arc
- [Register an AI Agent](https://docs.arc.network/arc/tutorials/register-your-first-ai-agent.md): ERC-8004 onchain identity and reputation
- [Create an ERC-8183 Job](https://docs.arc.network/arc/tutorials/create-your-first-erc-8183-job.md): Escrow, deliverables, settlement

## App Kit — Bridge, Swap, Send

- [App Kit Overview](https://docs.arc.network/app-kit.md): Payment and liquidity workflows across chains
- [Install App Kit](https://docs.arc.network/app-kit/tutorials/installation.md): Core package and adapters
- [Adapter Setups](https://docs.arc.network/app-kit/tutorials/adapter-setups.md): Viem, Ethers, Solana, Circle Wallets

### Bridge
- [App Kit: Bridge](https://docs.arc.network/app-kit/bridge.md): Transfer USDC across chains
- [Quickstart: EVM to EVM](https://docs.arc.network/app-kit/quickstarts/bridge-between-evm-chains.md): Bridge between EVM chains
- [Quickstart: Solana to EVM](https://docs.arc.network/app-kit/quickstarts/bridge-between-solana-and-evm.md): Bridge Solana to EVM
- [Quickstart: Circle Wallets](https://docs.arc.network/app-kit/quickstarts/bridge-with-circle-wallets.md): Bridge with Circle Wallets adapter
- [Estimate Costs](https://docs.arc.network/app-kit/tutorials/bridge/estimate-costs.md): Preview gas and fees
- [Collect Bridge Fees](https://docs.arc.network/app-kit/tutorials/bridge/collect-bridge-fee.md): Custom fee collection
- [Configure Speed](https://docs.arc.network/app-kit/tutorials/bridge/configure-transfer-speed.md): Balance speed vs cost
- [Specify Recipient](https://docs.arc.network/app-kit/tutorials/bridge/specify-recipient-address.md): Send to different address
- [CCTP Forwarding](https://docs.arc.network/app-kit/tutorials/bridge/use-forwarding-service.md): Forwarding Service
- [Bridge Fees](https://docs.arc.network/app-kit/concepts/bridge-fees.md): Fee breakdown
- [Error Recovery](https://docs.arc.network/app-kit/references/bridge-error-recovery.md): Troubleshooting failed bridges

### Swap
- [App Kit: Swap](https://docs.arc.network/app-kit/swap.md): Token swaps on same chain
- [Quickstart: Same-Chain Swap](https://docs.arc.network/app-kit/quickstarts/swap-tokens-same-chain.md): Swap tokens on one chain
- [Quickstart: Crosschain Swap](https://docs.arc.network/app-kit/quickstarts/swap-tokens-crosschain.md): Swap + bridge
- [Estimate Swap Rate](https://docs.arc.network/app-kit/tutorials/swap/estimate-swap-rate.md): Pre-swap estimates
- [Slippage / Stop Limit](https://docs.arc.network/app-kit/tutorials/swap/set-slippage-tolerance-or-stop-limit.md): Rate protection
- [Collect Swap Fees](https://docs.arc.network/app-kit/tutorials/swap/collect-swap-fee.md): Custom fee collection
- [Swap Fees](https://docs.arc.network/app-kit/concepts/swap-fees.md): Fee breakdown

### Send
- [App Kit: Send](https://docs.arc.network/app-kit/send.md): Wallet-to-wallet on same chain
- [Quickstart: Send Tokens](https://docs.arc.network/app-kit/quickstarts/send-tokens-same-chain.md): Send tokens between wallets

### Reference
- [SDK Reference](https://docs.arc.network/app-kit/references/sdk-reference.md): Full API reference
- [Supported Blockchains](https://docs.arc.network/app-kit/references/supported-blockchains.md): Chains and tokens

## Tools and Infrastructure

- [Block Explorers](https://docs.arc.network/arc/tools/block-explorers.md): Etherscan-compatible explorers
- [Node Providers](https://docs.arc.network/arc/tools/node-providers.md): RPC access providers
- [Data Indexers](https://docs.arc.network/arc/tools/data-indexers.md): APIs and sub-graphs
- [Account Abstraction](https://docs.arc.network/arc/tools/account-abstraction.md): AA providers and paymasters
- [Compliance](https://docs.arc.network/arc/tools/compliance-vendors.md): Analytics and screening tools
- [Explorer](https://testnet.arcscan.app): Arc Testnet block explorer
- [Faucet](https://faucet.circle.com): Testnet token faucet

## More Circle Skills

Building beyond Arc? Circle offers skills for the full platform:

| Product | Skill |
|---------|-------|
| USDC | [use-usdc](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md) |
| Wallets (overview) | [use-circle-wallets](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md) |
| Developer-Controlled Wallets | [use-developer-controlled-wallets](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md) |
| User-Controlled Wallets | [use-user-controlled-wallets](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md) |
| Modular Wallets | [use-modular-wallets](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md) |
| Gateway / Nanopayments | [use-gateway](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md) |
| Smart Contracts | [use-smart-contract-platform](https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md) |

Full Circle developer docs: [developers.circle.com/llms.txt](https://developers.circle.com/llms.txt)