Ethereum’s development community has officially confirmed the dates for the upcoming Glamsterdam event, a gathering that brings together researchers, developers, and ecosystem partners to discuss the future of the network. While the announcement has been met with enthusiasm, the Ethereum Foundation also issued a stark warning: the presence of so‑called “fake” builders could jeopardize the smooth operation of the chain. In this article we will unpack what these fake builders are, how free test Ether can be misused to give them an advantage, why they might withhold transaction payloads, and what the shortened review windows for client teams mean for the upcoming Sepolia testnet launch.
### What Is Glamsterdam? Glamsterdam is a hybrid conference and hackathon that takes place in Amsterdam, merging the words “glamour” and “Amsterdam” to convey a sense of high‑profile collaboration in a city known for its vibrant tech scene. The event is scheduled for early November and will feature a series of workshops, panel discussions, and hands‑on coding sessions focused on Ethereum’s roadmap, including upgrades such as the upcoming Shanghai‑style hard forks, layer‑2 scaling solutions, and improvements to the consensus layer.
Participants range from seasoned core developers to newcomers eager to contribute to open‑source projects, and the agenda is designed to foster both deep technical discourse and community building. ### The Threat of ‘Fake’ Builders In the context of Ethereum’s proof‑of‑stake (PoS) architecture, a “builder” is an entity that assembles blocks by selecting transactions from the mempool, ordering them, and attaching a payload that validators then propose to the network. Builders compete in a market where they are paid fees for including transactions, and the most lucrative bundles often win the right to be proposed.
However, not all builders act in good faith. Fake builders—sometimes referred to as “MEV‑extraction bots” or “adversarial block producers”—may engage in tactics that undermine network efficiency.
One of the primary concerns is that fake builders can use free test Ether, which is distributed by the Ethereum Foundation to developers for testing purposes on testnets such as Sepolia and Goerli. While the intention behind these airdrops is to lower the barrier to entry for experimentation, malicious actors can exploit the free tokens to outbid honest builders in the block‑building market. By offering higher fees, they can secure priority inclusion of their own transactions, effectively crowding out legitimate traffic and creating a distorted fee market. ### Withholding Transaction Payloads Another risky behavior exhibited by fake builders is the deliberate withholding of transaction payloads.
In a typical block‑building process, the builder assembles a list of transactions, computes the resulting state transition, and then shares the payload with validators for verification. If a builder withholds the payload—perhaps by delaying its release or providing an incomplete set of data—validators may be forced to make decisions with insufficient information. This can lead to chain stalls, where the network experiences a temporary slowdown because validators are waiting for the missing data before they can finalize a block. The consequences of such stalling are not merely theoretical.
Prolonged delays can increase the time it takes for transactions to be confirmed, raise the risk of temporary forks, and erode user confidence in the network’s reliability. Moreover, in a PoS system where validator rewards are tied to timely block proposals, any disruption can affect the overall economics of staking, potentially disincentivizing participation.
### Shortened Review Periods for Client Teams Compounding the issue of fake builders is the fact that Ethereum’s client teams—maintainers of software implementations such as Geth, Nethermind, Besu, and Lighthouse—are operating under a compressed review timeline ahead of the Sepolia testnet upgrade. Historically, client teams have enjoyed a generous window of several weeks to review, test, and merge code changes before a major network upgrade.
For the upcoming Sepolia rollout, the review period has been halved, giving teams only about half the usual time to vet new features and security patches. This acceleration is driven by a desire to iterate quickly and bring improvements to users faster.
However, it also raises the stakes for thorough testing. With less time to scrutinize code, the probability of bugs slipping through increases, especially when the codebase is being modified to counteract the tactics of fake builders. If a vulnerability related to payload handling or fee market manipulation goes undetected, it could be exploited on the live network, amplifying the impact of malicious actors. ### Mitigation Strategies The Ethereum community is not standing idle in the face of these challenges.
Several mitigation strategies are being discussed and, in some cases, already implemented: 1. **Enhanced Monitoring of Testnet Activity** – By closely tracking the behavior of builders on Sepolia, the foundation can identify patterns indicative of malicious activity, such as unusually high fee bids from newly funded accounts. 2.
**Rate‑Limiting Free Test Ether Distribution** – Adjusting the distribution mechanism to limit the amount of test Ether any single entity can claim may reduce the ability of fake builders to amass large balances for outbidding. 3.
**Payload Availability Protocols** – Introducing protocols that require builders to commit to publishing full payloads within a strict timeframe, with penalties for non‑compliance, can discourage withholding tactics. 4. **Extended Audits for Critical Changes** – Even with a shortened overall timeline, critical sections of the code—especially those handling block assembly and validation—will undergo extended peer review and formal verification.
5. **Community Reporting Channels** – Providing clear channels for developers and validators to report suspicious builder behavior helps the community respond quickly to emerging threats.
### What This Means for Participants of Glamsterdam Attendees of Glamsterdam should be aware that the discussions will likely delve deeply into these security concerns. Workshops may cover how to design resilient builder strategies, how to implement robust monitoring tools, and how to contribute to the development of anti‑MEV (Miner Extractable Value) solutions. For developers planning to experiment on Sepolia, it is advisable to: - Use modest amounts of test Ether and avoid creating large, centralized wallets that could be flagged as potential fake builders. - Participate in the community’s reporting mechanisms by flagging any anomalous fee bidding behavior.
- Contribute code or documentation that helps improve payload availability checks. By engaging proactively, participants can help shape a more secure and efficient Ethereum ecosystem. ### Looking Ahead The confirmation of Glamsterdam’s dates is a positive sign that the Ethereum community continues to prioritize collaboration and innovation. At the same time, the warning about fake builders serves as a reminder that the network’s health depends on vigilance against both technical and economic attacks.
As the Sepolia testnet prepares for its upcoming upgrade, the combination of careful monitoring, refined protocols, and community involvement will be essential to ensure that the chain remains resilient. In summary, while the excitement surrounding Glamsterdam is well‑founded, stakeholders must remain cognizant of the risks posed by malicious builders leveraging free test Ether and employing payload‑withholding tactics. With shortened review periods for client teams, the margin for error is narrower, making the community’s collective effort to identify and mitigate these threats more critical than ever. By fostering open dialogue, encouraging responsible testing practices, and implementing robust safeguards, Ethereum can continue its trajectory toward a more secure, scalable, and inclusive future.