Alto Bundler


In public beta. While Alto is functional, it is still in active development and is not feature-complete. If you would like to contribute, feel free to open a Github Issue (opens in a new tab) or a Pull Request (opens in a new tab)

Alto ⛰️ is a performant, type-safe ERC-4337 bundler written in Typescript.

Our focus is on full type safety, transaction inclusion reliability (even in the case of sudden gas price spikes or chain reorgs), as well as transaction inclusion speed.


Learning-oriented lessons that take you through a series of steps to complete a project. Most useful when you want to get started with Pimlico. They all involve the Alto Bundler.

  • Tutorial 1 leverages the Alto Bundler to create a simple user operations and have it bundled on-chain.
  • Tutorial 2 leverages the Alto Bundler again, but using the ERC-20 paymaster instead of the Verifying Paymaster


References provide specific technical descriptions. They are most useful when you need detailed information about Pimlico's APIs.