Base’s Denim upgrade is live on mainnet, bringing full canonical blocks every 200 milliseconds—five per second—to the Coinbase-incubated Layer 2, according to a project statement reported by The Block.
The report was published on November 6, 2026, at 04:00 UTC+08:00. Denim is Base’s fourth independent network upgrade, following Azul, Beryl and Cobalt, all implemented in 2026.
Block production and the Flashblocks migration
Denim retires Flashblocks and changes how the pending block tag works. Each block now follows its parent exactly 200 milliseconds later, with the protocol enforcing that interval rather than relying on the sequencer’s clock.
Base described the change as making block production “simpler, more consistent, and more reliable.” That is the project’s assessment; the report does not provide independent performance measurements.
For application developers, the documented migration requirement is clear: applications that relied on Flashblocks must move to standard canonical block subscriptions.
BaseTime adds millisecond timestamps
The upgrade introduces BaseTime, giving smart contracts access to Unix timestamps in milliseconds. The existing Ethereum-compatible block.timestamp retains its whole-second resolution, while new RPC fields supply millisecond timestamps for blocks, transactions and logs.
Base framed more frequent state updates and precise timing as requirements for the trading, financing and payments use cases it is targeting.
B20 transfer and compliance changes
Denim also updates controls for tokens using Base’s B20 standard. According to Base, the upgrade:
- Introduces reusable compliance policies through a NOT operator.
- Extends transfer-executor restrictions to direct transfers.
- Blocks transfers, mints and seizures that would send tokens to the token contract’s own address.
These are changes to token transfer rules and compliance controls, distinct from the upgrade’s block-production and timestamp features.
Where Denim fits in Base’s upgrade path
Base launched in 2023. Its preceding independent upgrades introduced different pieces of the network’s infrastructure:
- Azul: a new client stack and multiproof system.
- Beryl: the B20 token standard.
- Cobalt: conditional transactions and expanded B20 compliance features.
Denim is a mainnet deployment, not a testnet announcement. The report documents the technical changes and the migration requirement for Flashblocks-dependent applications, but does not establish how widely applications have adopted the new interfaces.