Ethereum's Glamsterdam Upgrade Enters Final Testing as Developers Lock In Builder Separation

Ethereum's developers have moved Glamsterdam, the network's next scheduled hard fork, into its final development stage. According to CoinDesk, client teams are now running developer networks, the closed testing environments used to trial new code before it reaches public testnets, with the complete set of Ethereum Improvement Proposals (EIPs) bundled into the fork.

Glamsterdam updates both halves of the protocol at once. The execution layer changes (codenamed Amsterdam) and the consensus layer changes (codenamed Gloas) introduce Enshrined Proposer-Builder Separation (ePBS), which builds the split between who orders transactions and who proposes blocks directly into the protocol, and Block-Level Access Lists, which let nodes process transactions in parallel. Developers have not fixed an activation date and are targeting the second half of 2026, with an internal working target around the end of August that remains conditional on cross-client testing.

The change is structural rather than superficial. By enshrining proposer-builder separation, Ethereum is attempting to reduce the discretion that block builders hold over transaction ordering, the same discretion that enables the value extraction known as Maximal Extractable Value (MEV). The upgrade is one of the most significant changes to Ethereum's base layer since the 2022 move to proof-of-stake.

The core question is whether moving these rules on-chain genuinely reduces the difference between what the protocol enforces and what powerful intermediaries actually do, or whether it shifts the same concentration to a new layer of specialized builders.