EIP-4844

Formally titled "Shard Blob Transactions," EIP-4844 was the headline upgrade inside Ethereum's March 2024 Dencun hard fork. Its nickname, Proto-Danksharding, honors researchers Protolambda and Dankrad Feist, whose work shaped Ethereum's long-term data-scaling roadmap. Rather than sharding the network outright, the upgrade added a lightweight, temporary storage lane that rollups could start using immediately, without waiting years for the full sharding design to ship.

Technically, EIP-4844 introduces a new transaction type that carries one or more "blobs," fixed-size chunks of data around 128 KB each. A Ethereum block could originally hold up to six blobs, targeting three per block. Unlike ordinary transaction data, blob contents are invisible to the Ethereum Virtual Machine: smart contracts only see a cryptographic commitment proving the data exists and is correct. Because blobs don't need to persist forever, consensus clients delete them after roughly 18 days, keeping the chain lean while still letting anyone verify a rollup's data during the window that actually matters.

This matters because Layer 2 rollups such as Arbitrum, Optimism, and Base previously had to publish their batched transaction data as permanent, expensive calldata. Moving that data into blobs cut posting costs by roughly 90 percent within days of activation, dropping typical L2 fees from around a dollar to fractions of a cent on several networks.

EIP-4844 was always framed as a stepping stone rather than a finish line. Ethereum's 2025 Pectra upgrade doubled blob capacity, and the later Fusaka upgrade introduced Data Availability Sampling, letting nodes verify blob data without downloading all of it, pushing capacity further toward the roughly 128 blobs per slot envisioned under full danksharding.