What Pimlico actually does

To run an ERC-4337 system, you need node infrastructure that operates outside the standard Ethereum mainnet mempool. This is where Pimlico comes in.

Pimlico is an infrastructure provider that operates two critical services for Account Abstraction:

1. alto-bundler: A high-speed, open-source Bundler client that listens to the alternative mempool for UserOperations and packages them into blockchain transactions.
2. verifying-paymaster: A service that generates cryptographic sponsorship signatures, allowing web applications to cover their users' gas fees gaslessly.

---

1. The Role of the Bundler

Standard RPC nodes (like Infura or Alchemy) do not understand the UserOperation object. If you send a UserOp to eth_sendRawTransaction, the node will throw a parsing error.

Pimlico's Bundler exposes a set of custom RPC endpoints (defined in the ERC-4337 specification) such as:

• eth_sendUserOperation
• eth_estimateUserOperationGas
• eth_getUserOperationReceipt

When your React app submits a UserOp, it sends it to Pimlico's bundler endpoint. The bundler validates the gas parameters, holds the UserOp in its local queue (alt-mempool), merges it with other UserOps, and broadcasts the bundle as a single standard transaction to the network.

---

2. The Paymaster Integration

Pimlico provides the API endpoints that allow developers to configure sponsorship rules:

• Sponsor All: The app pays for all transactions matching a specific smart contract method (e.g., liking a post on Socio3 V2).
• Token-based payment: Users pay gas fees using ERC-20 tokens (like USDC) instead of native gas tokens. Pimlico's paymaster automatically swaps the USDC to cover the native gas fee behind the scenes.
• Rate Limits: Restricting gas sponsorship per user or IP address to prevent abuse.

In Socio3 V2, Pimlico acts as the communication layer that enables MetaMask-free, gasless social actions.