Choose a paymaster kit 2026 provider
Selecting the right ERC-4337 paymaster infrastructure is the foundation of your gas sponsorship strategy. In 2026, the ecosystem has matured, but the choice between Pimlico, ZeroDev, and Biconomy depends on your specific chain requirements and developer experience. You need a provider that offers stable SDKs, broad chain support, and transparent pricing.
Start by evaluating the supported networks. If you are building on Ethereum mainnet or major Layer 2s like Arbitrum or Base, Pimlico offers the most robust documentation and community support. For developers prioritizing ease of integration and rapid prototyping, ZeroDev’s account abstraction tools provide a streamlined path. Biconomy remains a strong option if you require multi-chain deployment with a focus on user-friendly onboarding flows.
| Provider | Key Chains | SDK Ease | Pricing Model |
|---|---|---|---|
| Pimlico | ETH, Base, Arbitrum | High | Pay-as-you-go |
| ZeroDev | ETH, Polygon, BSC | Very High | Free tier + usage |
| Biconomy | Multi-chain EVM | High | Subscription + usage |
Review the SDK quality and documentation before committing. Poorly maintained SDKs lead to integration delays and production bugs. Check the provider’s GitHub activity and issue response times. Additionally, verify the gas token support. Most providers now support ERC-20 fee payments, but you must ensure your chosen token is supported on your target chain.
Finally, consider the long-term viability of the provider. The paymaster landscape is competitive, and some smaller providers may merge or shut down. Stick to established players with significant funding and active development teams. This ensures your gas sponsorship feature remains stable as your user base grows.
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Integrate the smart account SDK
To enable gas sponsorship, your application must first recognize the user as a smart contract wallet rather than an externally owned account (EOA). This integration allows the Paymaster to intercept transactions and pay the gas fees on the user’s behalf. We recommend using a standard ERC-4337 compatible SDK, such as SafeWallet or MetaMask Smart Accounts, to handle the underlying account logic.
Begin by installing the specific SDK for your chosen smart account provider. For SafeWallet, install @safe-global/safe-ethers-lib and @safe-global/safe-apps-sdk. For MetaMask, use @metamask/smart-account. Ensure your project’s TypeScript definitions are updated to recognize the new account types.
Create a singleton instance of the smart account in your frontend configuration. Pass your wallet provider (e.g., MetaMask or WalletConnect) and the desired chain ID to the SDK constructor. This instance will serve as the bridge between the user’s browser wallet and the Paymaster kit, handling signature generation and transaction encoding.
Update your transaction submission logic to use the SDK’s buildUserOp method instead of standard sendTransaction. The UserOp builder automatically packages the call data, nonce, and gas limits into the ERC-4337 format required by the Paymaster. Verify that the paymasterAndData field is left empty at this stage, as the Paymaster will fill it during the bundler submission.
Before connecting to mainnet, test the integration using a local bundler like Huddle01 or a testnet provider such as Alchemy or Infura. Send a small test transaction with a $0 value to ensure the Paymaster correctly intercepts the request and returns the sponsored UserOp. Check the bundler’s response logs to confirm the account is recognized and the gas sponsorship logic is active.
This setup ensures that your application is ready to handle gasless transactions. The SDK handles the complex cryptography of the smart account, while the Paymaster kit manages the fee payment logic.
Configure gas sponsorship logic
Setting up the Paymaster Kit to sponsor gas fees requires precise configuration to balance user experience with operational sustainability. The goal is to abstract gas costs from the end-user while ensuring the sponsor retains control over spending limits and eligible transactions.
Establish clear caps on gas spending to prevent fund draining. Configure daily or per-transaction limits for both native token (ETH) and ERC-20 token sponsorship. This ensures that even if a contract is compromised, the financial exposure remains contained within predefined boundaries.
Restrict sponsorship to specific smart contracts or function signatures. By whitelisting only approved contracts, you prevent malicious actors from redirecting sponsored gas to unauthorized dApps. This step is critical for maintaining the integrity of your gas sponsorship program.
Integrate robust validation checks within the paymasterValidation function. Ensure that the sponsor verifies the user's eligibility, such as holding a minimum token balance or having completed a specific on-chain action. This logic acts as the gatekeeper, ensuring only qualified users benefit from gas sponsorship.
If your application supports ERC-20 token payments for gas, configure the Paymaster to accept these tokens. Set up the necessary approval flows and ensure the Paymaster can deduct fees from the user's token balance or sponsor the fees using a designated ERC-20 token. This adds flexibility for users who prefer not to hold native gas tokens.
By following these steps, you create a secure and user-friendly gas sponsorship system. This approach not only enhances the onboarding experience for new users but also provides you with the necessary controls to manage costs effectively.
Test the paymaster flow
Testing ensures your gas sponsorship logic works before users send real funds. You need to verify that transactions are bundled correctly, the sponsor covers the gas, and the user experience remains seamless on a testnet.
Deploy your smart contracts to a testnet like Sepolia or Holesky. Use a testnet faucet to fund both the user wallet and the paymaster contract with test ETH. This environment mimics mainnet behavior without risking real capital.
Initiate a transaction from the user wallet that would normally require gas. Configure the transaction to use your paymaster’s address as the fee payer. Verify that the transaction is accepted by the node and included in a block.
Check the transaction receipt on a block explorer. Confirm that the gas fee was deducted from the paymaster’s balance, not the user’s. Ensure the gasUsed and gasPrice values match your sponsorship logic.
Intentionally underfund the paymaster or trigger a revert condition in your smart contract. Verify that the user receives a clear error message and that the transaction does not hang or result in partial state changes.
FAQ about paymaster kits
The following questions address common technical hurdles when implementing ERC-4337 Paymaster modules for gas sponsorship.
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