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Basics

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What is Account Abstraction (ERC-4337)?

Account Abstraction gives onchain accounts programmable logic, enabling features like batched transactions, gas sponsorship, and passkey authentication. Operations are packaged as “userOperations” and processed through specialized components:
  • Bundler: Collects userOperations and submits them to the network
  • Entrypoint: The contract that orchestrates the transaction flow
  • Paymaster: A contract that covers gas fees on behalf of the user
  • Smart Account: A programmable wallet that validates signatures and executes transactions

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Do I need the Paymaster contract address to sponsor transactions?

No. CDP Paymaster combines Paymaster and Bundler into a single endpoint. You just use your Paymaster URL: 
const hash = await bundlerClient.sendUserOperation({
  calls: [{
    abi: ContractAbi,
    functionName: 'mint',
    to: '0xContractAddress',
  }],
});

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Can I sponsor transactions for any wallet?

Gas sponsorship only works with smart accounts, not traditional EOAs. With EIP-7702, EOAs can be upgraded to smart accounts, enabling gas sponsorship.

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What’s the difference between an EOA and a smart account?

FeatureEOASmart Account
ControlSingle private keyOnchain contract code
CreationInstant (no deployment)Requires contract deployment
FunctionalityBasic transfers onlyBatching, custom auth, programmable logic
Gas & FeesMust hold ETHGas sponsorship, stablecoin payments
RecoveryNo built-in recoveryGuardian-based recovery possible

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Which SDKs can I use with CDP Paymaster?

  • CDP Embedded Wallets — Use useSendUserOperation with useCdpPaymaster: true
  • CDP Server Wallets — Use Managed Mode for automatic Paymaster integration
  • Viem + Permissionless — Direct bundler/paymaster client integration
  • Any ERC-7677 compatible SDK
See the examples repository for implementations.

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Can I use the Paymaster on testnet?

Yes. CDP Paymaster supports Base Mainnet and Base Sepolia. Select your network in CDP Portal.

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Can I use third-party bundlers with CDP Paymaster?

No. CDP Paymaster works exclusively with CDP’s Bundler—they’re combined into a single endpoint.

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Billing

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How is billing calculated?

actualGasUsed × ethPriceUsd × 1.07
You’re charged based on actual gas used (from the UserOperationEvent) multiplied by ETH price in USD, plus a 7% markup. You’re billed monthly in USD via your CDP account.

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Where can I see my bill and usage?

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How can I get Paymaster credits?

Developers can apply for up to $15,000 in gas credits, with additional bonuses available through the Base Gasless Campaign. Apply for credits

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EIP-7702

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What is EIP-7702?

EIP-7702 (part of Ethereum’s Pectra upgrade) lets you upgrade an EOA into a smart account at the same address by delegating to a smart contract’s code.

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What’s the difference between EIP-7702 and ERC-4337?

  • EIP-7702: Upgrades EOAs to smart accounts via code delegation
  • ERC-4337: The Account Abstraction infrastructure (userOps, paymasters, bundlers)
They work together — EIP-7702 lets you add ERC-4337 support to existing EOAs.

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Does CDP Paymaster support EIP-7702?

Yes. CDP Paymaster can sponsor transactions for EOAs that have been upgraded to support ERC-4337 validation.
CDP Wallets do not yet support EIP-7702 upgrades directly. If you upgrade an EOA using other tools (like viem), CDP Paymaster can sponsor transactions for that upgraded account.

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How do I upgrade an EOA with EIP-7702?

See the Security page for secure upgrade patterns and resources. The key points:
  • Don’t delegate directly to a wallet implementation (front-running risk)
  • Use EIP7702Proxy and call setImplementation atomically

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How can I tell if a wallet is upgraded?

Call eth_getCode(address). If the result is not 0x, the account is a smart account.