Solana switches to Alpenglow consensus, aiming to cut finality to about 150 milliseconds

Solana switched to a new consensus protocol, Alpenglow, on Wednesday, October 21, replacing the TowerBFT system it had used since its launch in March 2020, The Block and Decrypt reported. Anza, the developer behind the upgrade, says it cuts the time for a transaction to become final from 12.8 seconds to about 150 milliseconds.

What changed

Consensus is the process by which a blockchain's validators agree on which transactions are final. Anza said Alpenglow reached mainnet-beta at slot 459,653,000 at about 14:00 UTC, The Block reported.

Finality is the point after which a transaction cannot be reversed. According to Anza, it falls from 12.8 seconds to about 150 milliseconds. The Alpenglow proposal, SIMD-0326, gives TowerBFT's finality time as 12.8 seconds and says Alpenglow completely replaces the old consensus protocol. Anza said the faster finality is aimed at use cases such as exchanges and merchants.

The 150-millisecond figure is a design target. Shortly after launch, the Solana Foundation's Alpenglow dashboard showed 6.6-second finality, Cointelegraph reported.

Anza said the upgrade went through public testing that included red-team exercises, penetration testing, repeated migration rehearsals, and a security competition, The Block reported.

What comes next

Anza has outlined further changes, including Rotor and geographically aware leader rotation, along with a research design called Quantumglow and a proposal, SIMD-0370. None has a confirmed release date, The Block reported.

Why it matters

Faster finality matters most to exchanges, payment processors, and market makers, which wait for transactions to be final before crediting deposits or settling trades. If finality approaches the 150-millisecond target in practice, it would shorten the time funds are in transit between venues.

What it could mean for traders

Exchanges set their own confirmation requirements for deposits, so users will see the benefit only if venues lower their waiting times for Solana. Measured finality after the switch, and any change in exchange deposit policies, are the indicators to watch.