Blob Transaction

Overview

Blob transactions, also called type-3 transactions, let Ethereum rollups publish large batches of data in a form that is cheaper than permanent execution calldata. The transaction contains commitments to blobs, while the blob data is propagated and stored by the consensus layer for a limited retention period.

The Ethereum Virtual Machine cannot directly read blob contents. Smart contracts can access a blob commitment-related value but not use blobs as permanent contract storage. This design separates temporary data availability from ordinary execution data.

Blob space has its own fee market. A transaction pays ordinary execution gas and a separate blob fee based on blob demand. The mechanism supports rollup scaling because users and verifiers can obtain the data needed to reconstruct layer-2 state during the availability window without forcing every byte to remain permanently in Ethereum’s execution state.

A blob transaction is not a transaction that sends a “blob token,” and it is not a generic name for any large blockchain transaction. It is a specific Ethereum protocol transaction type.

Blob transactions introduced a separate data-availability resource and fee market. They still pay ordinary execution gas for the transaction envelope and any EVM work, while blob gas is priced independently according to network demand. This separation makes rollup data publication less dependent on competition for execution calldata.

The transaction contains commitments and proofs that allow the network to verify the associated blob data. The data is intended for temporary availability so rollup participants can reconstruct and verify batches; Ethereum’s permanent state does not store the blob contents indefinitely. Applications should not use blobs as durable file storage or assume contracts can retrieve old blob data later. For payment users, blob transactions are mainly infrastructure: they can lower rollup operating costs, but final transaction fees still depend on rollup policy, congestion, compression, and execution requirements.