What "killer features" are hidden in the Ethereum Glamsterdam upgrade championed by Vitalik?

Ethereum founder Vitalik Buterin has been very active on social media recently, first reflecting on the previous Layer 2 approach, then outlining new plans for Ethereum’s future roadmap.

This has increased expectations for the Ethereum Glamsterdam upgrade scheduled for the first half of this year. What are the key features of this major update?

From “Predecessor” to “Successor”

Before understanding Glamsterdam, we need to look at its “predecessor”—the Fusaka upgrade.

Fusaka is a data layer upgrade for Ethereum. It introduced two key features: PeerDAS and EOF.

PeerDAS: Download only a small portion of data instead of everything. Similar to sampling surveys—asking a small subset of people to infer the whole population. Combined with zero-knowledge proofs, even if only 1/16 of the data is downloaded, data integrity can be verified, greatly increasing Ethereum’s network throughput.

EOF: Essentially an internal reform of the EVM. It makes the EVM’s code structure clearer, more modular, and easier to optimize. EOF is like renovating the EVM, making its internal structure more rational.

If Fusaka is a “data layer upgrade,” then Glamsterdam is an “execution layer upgrade.” Fusaka mainly addresses “how to transmit data,” while Glamsterdam focuses on “who produces blocks.”

Core of Glamsterdam—ePBS and BAL

ePBS separates block packaging and validation processes—block builders package transactions, proposers propose blocks, and validators verify blocks. Each role performs its own duties, allowing block builders to pack more transactions aggressively because proposers and validators will check their work, alleviating security concerns.

Can Ethereum do this now? Yes, but it relies on relays like Flashbots to separate “proposing” and “building.” Validators only propose blocks, while builders earn MEV (Maximal Extractable Value) by packaging transactions.

This creates a black box, requiring trust in third-party relays, which can lead to failures, censorship, attacks, or centralization.

ePBS embeds this separation mechanism directly into the protocol (EIP-7732), making it “on-chain auction + protocol enforcement,” solving trust issues and improving network efficiency.

The Block Access List (BAL) allows block proposers to inform validators in advance: “This block’s transactions will access these accounts and storage locations.” With this info, validators can prepare by loading data from disk into memory. They can then verify multiple transactions in parallel instead of one by one—like an assembly line: instead of one worker handling the entire product, multiple workers handle different parts simultaneously.

Combining these two creates a dual enhancement—improving efficiency and resisting censorship.

However, for ePBS to reach its full potential, another piece is needed—Fork Choice with Mandatory Inclusion List (FOCIL). FOCIL allows validators to publish a list of transactions that must be included. If builders omit these transactions, validators can reject the block based on fork choice rules. This provides validators with a “last line of defense” against excessive censorship by builders.

Implementing both ePBS and FOCIL simultaneously is complex. Therefore, FOCIL is expected to arrive in the second upgrade later this year, called Hegotá.

Potential Impact of Glamsterdam

Beyond ePBS and BAL, the upgrade will include gas fee re-pricing and multi-dimensional gas models. This will make transactions cheaper for ordinary users and increase overall network capacity, though it may raise costs for some developers building new states.

For stakers, the revenue model becomes clearer, with greater block selection rights and smoother MEV earnings. This could lead to changes in the MEV ecosystem—applications relying on current MEV extraction methods might need to adjust.

As validators gain more power, new application opportunities will emerge—such as “validator services” that help validators select blocks more effectively.

But Glamsterdam is unlikely to be perfect. As mentioned earlier, ePBS will be part of the upgrade but without FOCIL, it remains an incomplete version. Its complexity is high, and it grants more power to validators. Besides stability after deployment, there’s concern whether decentralization might lead to new forms of centralization at the validator level.

Vitalik has also acknowledged that “ePBS is just to prevent centralization of block building from spreading to staking, but the centralization of block builders themselves remains.” Toxic MEV (sandwich attacks, frontrunning) may just shift elsewhere.

Long-term, the biggest significance of the Glamsterdam upgrade may be “decentralization.” Vitalik’s dedication to decentralization theory and his idealism could increase trust in Ethereum adoption by traditional finance and the wider world. Time will tell if this persistence will be reflected in Ethereum’s price.

Since last year, Ethereum’s major upgrades have increased to twice a year. No longer resting, Ethereum is now “racing against time,” and may truly restore its glory.