ERC-4337 Bundle vs. Batch

What is a bundle?

A bundle is a group of user operations that a Bundler submits to the Entrypoint contract for routing to the senders' smart contract accounts.

In most cases, senders are only permitted to include a single user operation in a bundle. An exception to this rule occurs when the sender is staked with the Entrypoint contract, in such cases, they can send multiple operations in a single bundle. However, this is not a common for most accounts.

User operations in a bundle are mostly isolated from each other. This means if one user operation fails during its execution function, other operations can still succeed.

What is a batch (transaction batching)?

Transaction batching is a feature or benefit of Account Abstraction. A batch refers to a group of calls that a smart contract account can make inside a single user operation.

To use batching, a user must have a Smart Contract Account (SCA) that supports an execute batch function, and they must construct the entire batch before sending the fully constructed (single) user operation to the Bundler.

What is atomicity?

Atomicity refers to an "all or nothing" property of a group of calls within a batch, provided the smart contract account supports the feature, where if a single call in the batch fails, all the calls in the group will be reverted.

Does Alchemy's bundler support batching?

Alchemy's Bundler endpoint does not natively support batching. Batching needs to be handled by the smart contract account itself.