Crypto glossary
Blobs (EIP-4844, proto-danksharding)
Blobs are large, temporary data packets added to Ethereum blocks by EIP-4844 in March 2024, giving rollups a much cheaper place to publish their data.
EIP-4844, also called proto-danksharding, introduced a new transaction type that carries blobs of about 128 KB each. Unlike normal calldata, blob contents cannot be read by smart contracts, and nodes delete them after roughly 18 days. Only a short cryptographic commitment stays on chain permanently, enough to prove what the data was.
The upgrade went live with Dencun in March 2024 and is aimed at rollups, which need their data available for a while, not forever. Blobs have their own fee market, separate from gas, with a base fee that rises when demand exceeds a target number per block. L2 fees dropped sharply after launch, and the Pectra upgrade of May 2025 raised the blob target to increase capacity.
Cheap blob space helps users of L2s far more than Ethereum's own fee revenue. When blobs fill up, prices spike quickly, and anyone needing old data must rely on archives kept outside the protocol.
Example
A rollup that paid around $1 per transaction to post data as calldata can fit thousands of transactions into one blob costing a few cents when blob demand is below target.
