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Paymaster

Overview​

A paymaster is an optional Account Abstraction (AA) component that sponsors UserOperations and improves the user experience for cross-rollup applications.

In Ethera, paymaster support sits around the smart-account flow. It is not part of Ethera's cross-rollup coordination model, and it is not required for atomicity. Instead, it is one of the integration choices developers can use when they want a sponsored transaction experience.

Role in Ethera​

Ethera's cross-rollup coordination model is built around Mailbox Contracts, the Shared Publisher, and Two Phase Commit. A paymaster belongs to a different layer of the stack:

  • It works with AA and UserOperations
  • It can sponsor gas-related execution costs for supported flows
  • It is optional infrastructure, not a foundational Ethera contract

This distinction is reflected in Universal Bridge, where wallet and paymaster integrations are described as modular choices built on top of Ethera's coordination model.

When to Use a Paymaster​

Paymaster support is useful when an application wants to:

  • Reduce the need for users to maintain gas or funding balances on every participating chain
  • Present a more sponsored or gasless-style smart-account experience
  • Build around UserOperations instead of raw signed transactions

If your application is already using Ethera's AA flow, paymaster support can be a natural extension of that setup.

SDK Integration​

The Ethera SDK exposes optional paymaster integration through getPaymasterEndpoint in createComposeConfig.

This function allows an integration to resolve a paymaster endpoint from the requested chain and method.

const composeConfig = createComposeConfig({
  wagmi: wagmiConfig,
  accountAbstractionContracts: {
    [rollupA.id]: rollupsAccountAbstractionContracts,
    [rollupB.id]: rollupsAccountAbstractionContracts
  },
  getPaymasterEndpoint: ({ method, chainId }) => {
    return `https://paymaster.example.com/${chainId}/${method}`;
  }
});

When this function is configured, the SDK can resolve a paymaster endpoint for the requested chain and method, and use it during UserOperation preparation.

Paymaster RPC Methods​

The current SDK paymaster helpers use the following methods:

  • pm_getPaymasterStubData: Requests preliminary paymaster data during UserOperation preparation
  • pm_sponsorUserOperation: Requests the final sponsored paymaster data for the operation that will be submitted

At a high level, this flow lets the SDK:

  • Prepare the UserOperation
  • Request paymaster stub data
  • Request sponsored paymaster data for the final operation

For the SDK configuration surface and surrounding setup, see Ethera SDK.

Without a Paymaster​

If you do not use one, you can still build cross-rollup applications, but your signing and funding flow needs another way to cover execution costs for the smart-account path. In practice, that usually means the user or application is responsible for the gas funding strategy instead of relying on sponsorship.

Testnet Endpoint​

The Ethera Sepolia environment provides a paymaster endpoint for both rollups. The active endpoint is listed on Testnet.