proto-danksharding (EIP-4844)

Proto-danksharding is the first installment of danksharding, shipped in Ethereum's March 2024 Dencun upgrade as EIP-4844. It introduces the core new object — the data blob — and a separate fee market for it, but deliberately stops short of the hard part. It adds the data format, the transaction type, and the cheap pricing that rollups need today, while leaving data availability sampling for a later upgrade. In the meantime, every node still downloads every blob, which is acceptable at the modest blob counts launched.

Its purpose was to cut rollup costs immediately. Before blobs, rollups posted their compressed transaction data as ordinary calldata, competing for the same gas as every swap and transfer and inheriting that data permanently. Proto-danksharding gives them a dedicated, much cheaper lane: blobs are priced in their own blob-gas market (which floats independently of normal gas), and they are pruned after about 18 days instead of being stored forever. The effect on launch was dramatic — many rollups saw their data-posting fees fall by an order of magnitude, and L2 transaction costs dropped accordingly.

Crucially, proto-danksharding ships the forward-compatible scaffolding. The blob format, the KZG commitments, the new transaction type and the point-evaluation precompile are designed so that when full danksharding later adds sampling and many more blobs per block, the interface rollups build against does not change. Launch parameters were a target of 3 and a maximum of 6 blobs per block, each 128 KiB; the Pectra upgrade in 2025 raised these (to a target of 6 and maximum of 9) as confidence grew, with full danksharding's higher counts to follow once sampling is live.