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What is a Bundler?

💡 A Bundler is a crucial component in the smart account infrastructure. It validates and executes UserOperation transactions on smart contract wallets on behalf of users.

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Key Functions of Bundlers

  1. Acts as an EOA: Bundlers function like Externally Owned Accounts (EOAs) because all transactions on Ethereum must be triggered by an EOA.
  2. Enhances User Experience: Bundlers save users from creating and remembering private keys of EOAs to trigger smart contract wallet transactions. This preserves the core benefits of having a smart contract wallet.
  3. Optimizes Gas Usage: Bundlers are excellent for gas savings:
    • Executing each transaction typically costs a fixed overhead of 21,000 gas.
    • Bundled transactions spread this fixed cost over multiple operations, reducing overall gas costs.
    • Modifying storage in the same transaction becomes incrementally cheaper for each additional operation.
  4. Enables Efficient Execution: While Ethereum executes transactions linearly to avoid state conflicts, UserOperations can be executed as a bundle. Bundlers typically include at most one transaction per smart contract wallet address, preventing clashes when modifying state.
  5. Similarity to Block Builders: Bundlers share similarities with block builders, as both broadcast validated UserOperation transactions to public or private mempools.