Base blockchain cuts block time to 0.2 seconds after Denim upgrade

Base, the Coinbase-incubated Ethereum layer 2 network, activated its Denim upgrade on mainnet at 18:00 UTC on November 5, 2026. The upgrade reduces block generation time tenfold from two seconds to 200 milliseconds, producing five canonical blocks per second. Denim officially retires Flashblocks, introduces millisecond-level timestamp resolution via BaseTime, and enhances B20 token security rules. Smart contracts relying on block counts as timers now run ten times faster.

Reduction of block generation time

• ▪Denim reduces Base's canonical block generation time tenfold from two seconds to 200 milliseconds, producing five canonical blocks per second
• ▪Base block No. 53,556,127 was the network's first 200-millisecond block produced after the Denim upgrade activation

Activation of the Denim upgrade

• ▪Denim represents Base's fourth major upgrade on mainnet, following the Azul, Beryl, and Cobalt upgrades
• ▪Base, the Coinbase-incubated Ethereum layer 2 network, activated its Denim upgrade on mainnet at 18:00 UTC on Thursday, November 5, 2026
• ▪Base node operators were required to upgrade to base/base v1.5.1 or later to support the Denim upgrade

Retirement of Flashblocks

• ▪Flashblocks had operated on Base since July 2025 to stream partial transaction preconfirmations every 200 milliseconds between two-second blocks
• ▪Denim officially retires Flashblocks on Base, requiring applications using Flashblocks or the pending block tag to migrate to canonical RPC streams

Updates to the B20 token standard

• ▪Base said Denim blocks B20 token mints, transfers, and seizures targeted at a token contract's own address to prevent permanent asset locking
• ▪Denim updates Base's B20 token standard by adding a NOT operator for policy inversion and extending transfer-executor restrictions to direct token transfers