Solana’s Alpenglow upgrade cuts finality to a 150ms target

Solana activated Alpenglow on mainnet on October 21, replacing the validator voting system it had used since 2020 and targeting transaction finality in about 150 milliseconds. That could let exchanges, merchants and apps treat payments as settled sooner. The Decrypt report on Alpenglow’s launch said the change took effect at slot 459,653,000.

How does Alpenglow make a transaction final?

A transaction first reaches a validator, a computer that checks it and helps agree on the network’s records. Under the old TowerBFT system, validators wrote votes into later blocks and accumulated approvals over time. That process took about 12.8 seconds to reach full finality, according to Anza.

Alpenglow changes how those votes travel. Validators send votes directly to each other, and the votes carry weight based on each validator’s stake. The protocol combines approvals into certificates. It can make a block final after one voting round with enough stake, or after two rounds that each meet a lower threshold. Think of it as collecting signatures directly from the people who must approve a decision, instead of waiting for each signature to be copied into a later record.

Finality is the point at which an application can treat a transaction as locked in. Solana’s network upgrade tracker lists Alpenglow as live on mainnet, with a target of about 150 milliseconds, down from 12.8 seconds under TowerBFT. The target applies under normal network conditions; it is not a guarantee that every transaction will settle at that speed.

What changes for people sending SOL or stablecoins?

The main potential benefit is less waiting for an app or service to treat a payment as settled. An exchange could credit a deposit sooner, while a merchant could release goods after receiving a stablecoin payment. Some Solana apps already displayed a confirmation before full finality; Alpenglow shortens the wait for that stronger settlement assurance.

Users can keep their existing wallets. CoinDesk reported that transaction fees and the way applications run remain unchanged. The speedup happens in the network’s agreement process, so people do not need to switch wallets to use it. The time an individual sees on screen can still depend on the service processing the payment and when it receives finality information.

Why might Solana’s transaction charts look different?

Validator votes no longer appear as blockchain transactions under Alpenglow. That means dashboards that counted those votes may show lower transaction totals, even if users are still making the same number of payments and trades. Comparing activity before and after the upgrade will require separating user transactions from validator votes.

The upgrade therefore changes the network’s settlement mechanism and the way some activity is counted. Its user-facing promise is a shorter path from a transaction being submitted to an app treating it as irreversible. The 150-millisecond figure is a target; how quickly that benefit reaches a user depends on network conditions and the service involved.

Sources and documents

• Decrypt report on Alpenglow’s launch — decrypt.co
• network upgrade tracker — solana.com