Originally published by The Block on November 6, 2026, at 04:00 UTC+8 (November 5 at 20:00 UTC).
Base’s fourth independent mainnet upgrade, Denim, went live with full canonical blocks every 200 milliseconds, or five per second, according to a project statement shared with The Block on Thursday. The upgrade also changed timing tools for smart contracts and transfer controls for tokens using Base’s B20 standard.
Full blocks replace Flashblocks
Base, the Coinbase-incubated Layer 2 network, retired Flashblocks with Denim. Each canonical block—the network’s standard block—now follows its parent exactly 200 milliseconds later. The protocol enforces that interval rather than relying on the sequencer’s clock.
The upgrade also changes how the pending block tag works. Applications that relied on Flashblocks must migrate to standard canonical block subscriptions, according to Base. The project described the changes as making block production “simpler, more consistent, and more reliable.”
BaseTime adds finer timing for smart contracts
Denim introduces BaseTime, which gives smart contracts access to Unix timestamps measured in milliseconds. The Ethereum-compatible block.timestamp remains unchanged, with whole-second resolution.
New RPC fields also provide millisecond timestamps for blocks, transactions and logs. Base tied the need for more frequent state updates and precise timing to its focus on trading, financing and payments.
What changes for B20 tokens?
For tokens using Base’s B20 standard, Denim adds or extends several compliance and transfer controls:
- Reusable compliance policies using a
NOToperator. - Transfer-executor restrictions that now also apply to direct transfers.
- A block on transfers, mints and seizures that would send tokens to the token contract’s own address.
These are changes to how B20 tokens can be controlled and moved; they are distinct from the network’s faster block schedule.
Where Denim fits in Base’s upgrade history
Denim follows Azul, Beryl and Cobalt, all implemented in 2026. These were Base’s first three independent upgrades since its 2023 launch:
- Azul: introduced a new client stack and multiproof system.
- Beryl: introduced the B20 token standard.
- Cobalt: added conditional transactions and expanded B20 compliance features.