Solana's Alpenglow consensus protocol is now running on devnet following a public handoff by Anza, the Solana software develo at 20:01 UTC on Sept. 25. The activation at slot 504,148,999 marks the retirement of TowerBFT on that cluster and opens a developer testing period before mainnet-beta migration. No mainnet-beta launch date has been announced.
Alpenglow's first phase replaces TowerBFT with Votor, changing how validators handle consensus votes. Under TowerBFT, validators post votes as transactions within blocks. Votor has validators exchange votes directly and collect results into certificates—a structural shift that reduces transaction finality from approximately 12.8 seconds to roughly 150 milliseconds, according to the Solana Foundation's Alpenglow migration guide.
For most Solana programs, the consensus switch does not affect the execution layer. The SVM, transaction formats, and fee mechanics remain untouched. Integrations around these programs will experience real changes, and the devnet now runs all of them.
Developers can identify a cluster's consensus regime using the `getAgGenesisCert` RPC method, which returns a certificate under Alpenglow and null under TowerBFT. The `solana alpenglow-genesis-info` CLI command also provides this information.
Alpenglow rolled to testnet one day earlier at slot 444,625,255 on Sept. 24 at 18:12 UTC. Anza initiated the devnet activation by flipping the Alpenglow feature gate at epoch 1167 on Sept. 25 at 16:51 UTC, triggering a 5,000-slot countdown before the consensus switch took effect roughly 17 minutes later.
The shift in vote handling mechanics will likely appear as a drop in transaction volume once Alpenglow reaches mainnet-beta. Solana Compass network data for Sept. 18 to 24 shows mainnet-beta processed 217.1 million vote transactions on Sept. 24 versus 168.8 million non-vote transactions, with votes representing 56 percent of total transaction count. Under Votor, vote transactions will no longer appear in the main transaction stream.
