> ## 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. # Account abstraction > Account abstraction providers on Arc, offering SDKs, paymasters, and smart wallet infrastructure for building flexible AA flows. Account abstraction (AA) replaces externally owned accounts (EOAs) with smart contract wallets that support programmable transaction validation, gas sponsorship, and batched operations. Arc supports the ERC-4337 standard, so you can use any compatible bundler, paymaster, or SDK from the providers below. ## Providers ### [Alchemy](https://www.alchemy.com/arc) Wallet APIs, a production bundler, and gas sponsorship so users can transact without holding gas tokens. * [**Wallet APIs**](https://www.alchemy.com/docs/wallets): Create and manage smart wallets with embedded signing and session keys. * [**Gas sponsorship**](https://www.alchemy.com/docs/wallets/transactions/sponsor-gas/sponsor-gas-evm): Sponsor transactions so users can transact without holding USDC for gas. ### [Biconomy](https://www.biconomy.io) Account abstraction toolkit offering modular smart accounts, paymasters, and bundlers as a service to simplify the user experience. ### [Blockradar](https://blockradar.co) Infrastructure and APIs for smart account management and transaction bundling, enabling scalable AA flows with minimal setup. ### [Circle Wallets](https://developers.circle.com/wallets) End-to-end platform for creating and managing secure Arc wallets and cryptographic keys. Supports ERC-20, ERC-721, and ERC-1155 standards. ### [Crossmint](https://www.crossmint.com) Wallet-as-a-service and AA capabilities to onboard users with email or OAuth-based accounts. ### [Dynamic](https://www.dynamic.xyz) Identity and wallet orchestration platform with native ERC-4337 support, enabling passkey wallets and flexible signer management. ### [MetaMask Embedded Wallets](https://docs.metamask.io/embedded-wallets/) Embedded wallet infrastructure with social login and multi-party computation (MPC) key management, plus smart accounts with managed bundlers and paymasters. ### [Para](https://getpara.com) Wallet and authentication suite for fintech and crypto applications, enabling flexible wallet management and transaction signing. ### [Pimlico](https://pimlico.io) Bundler and paymaster infrastructure for ERC-4337 smart accounts, offering sponsored transactions and reliable relay services. ### [Privy](https://www.privy.io) APIs and SDKs for embedded wallets and user authentication. Onboard users with email or social logins while maintaining full control over key management. ### [Thirdweb](https://portal.thirdweb.com/wallets) Full-stack toolkit with built-in AA support, SDKs, and a managed smart wallet layer. ### [Turnkey](https://docs.turnkey.com/reference/aa-wallets) Programmable key infrastructure for embedded wallets, transaction signing, and onchain automation with policy-based controls. ### [Zerodev](https://zerodev.app) Developer SDK for deploying and managing ERC-4337 smart accounts, with built-in session key and bundler support. Arc's account abstraction ecosystem is modular—you can mix SDKs, paymasters, and bundlers from multiple providers to design your smart account architecture.