EIP-4844 and Proto-Danksharding

Why Rollups Needed Cheaper Data

Layer-2 rollups (Arbitrum, Optimism, Base, zkSync, etc.) inherit their security from Ethereum by posting all their transaction data back to Ethereum. Before March 2024, they did this by stuffing the data into expensive 'calldata' fields in regular Ethereum transactions. Calldata is permanent — every Ethereum node stores it forever — and pricing it like permanent storage made rollup fees high. A typical L2 swap might cost $0.50–$1.00 in L1 data fees alone.

What EIP-4844 Did

EIP-4844 (Ethereum Improvement Proposal 4844), activated in the Dencun upgrade on March 13, 2024, added a new kind of data attachment called a 'blob.' Blobs are big chunks of data (~125 KB each, up to 6 per block) that piggyback on transactions but are stored separately and deleted after about 18 days. Because they're temporary, they're much cheaper than calldata. Rollups can use blobs to post their batch data, and rollup fees dropped by roughly 10x almost immediately.

What Users Saw

A typical Arbitrum swap that cost ~$0.50 pre-Dencun cost ~$0.04 post-Dencun. Base, Optimism, zkSync, and Linea saw similar drops. For users, this was the biggest single fee reduction in Ethereum L2 history. It's why L2 activity surged through 2024 — the same actions suddenly cost a tenth as much.

• Activated in the Dencun upgrade on March 13, 2024
• Adds 'blobs' — big temporary data attachments cheaper than calldata
• Cut L2 fees by ~10x almost overnight
• First step toward full 'danksharding' (a much bigger blob capacity in future upgrades)