Dencun upgrade adds blob transactions, sharply cutting L2 fees

Ethereum Foundation/Ethereum protocol upgrades

Dencun, combining Ethereum's Deneb (consensus) and Cancun (execution) upgrades, activated on mainnet on 13 March 2024. Its headline feature, EIP-4844 (proto-danksharding), added short-lived data blobs that rollups use to post transaction data, which cut layer-2 transaction fees significantly.

• Shard Blob Transactions (EIP-4844): temporary data storage that expires after a short period, not permanent.
• L2 impact: rollups use cheap, ephemeral blob space instead of permanent storage, reducing transaction costs.
• Upgrade components: consensus-layer Deneb (epoch 269568) and execution-layer Cancun; combined activation 13 March 2024, 13:55 UTC.
• Testing: successfully tested on testnets before mainnet deployment.