Vitalik Buterin Says Lean Ethereum Will Be Network’s Biggest Rebuild Since the Merge

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Ethereum co-founder Vitalik Buterin has described “Lean Ethereum” as the network’s next major protocol era, saying it is not a single upgrade but a collection of changes expected to reach Ethereum over the next three to four years. The comments came after Ethereum researchers met in Berlin to continue discussions on the protocol’s long-term direction. Buterin pointed to the updated Ethereum “strawmap,” a public draft roadmap that maps proposed upgrades across the consensus, data and execution layers.

The strawmap presents Ethereum’s long-term development around five major goals, including faster Layer 1 finality, gigagas-level Layer 1 throughput, teragas-scale Layer 2 data availability, post-quantum security and native Layer 1 privacy. The document describes these as Ethereum’s five “north stars,” including fast L1, gigagas L1, teragas L2, post-quantum L1 and private L1.

Lean Ethereum Is Not a One-Time Upgrade

Buterin said Lean Ethereum should not be treated as a single hard fork or one-time technical release. Instead, it is a series of protocol changes that will arrive gradually across future Ethereum upgrades. The roadmap frames the work as a deep rebuild of Ethereum’s core systems. It covers the consensus layer, execution layer and data layer, with changes expected to affect verification, cryptography, gas design, state management and client architecture.

In simple terms, Lean Ethereum is trying to make Ethereum:

• Faster at the base layer
• More scalable for rollups
• Safer against future quantum-computing risks
• More privacy-friendly by design
• Easier to verify and maintain over time

Buterin compared the scale of the effort to the Merge, Ethereum’s 2022 transition from proof-of-work to proof-of-stake. The difference is that Lean Ethereum is expected to unfold across multiple upgrades rather than through a single network event.

The direction also fits Buterin’s broader technical focus this year. In a recent cryptography essay, he discussed indistinguishability obfuscation, or iO, as a powerful but still impractical cryptographic primitive that could one day support private blockchain applications without relying on trusted operators. That long-term research focus aligns with Lean Ethereum’s push toward native privacy and stronger cryptographic foundations.

Glamsterdam and Hegotá Come Before the Lean Phase

Ethereum’s next named upgrade is Glamsterdam, which ethereum.org lists as an in-development upgrade planned for H2 2026. The upgrade focuses on Layer 1 scaling and includes enshrined Proposer-Builder Separation, known as ePBS, and Block-Level Access Lists, known as BALs. Glamsterdam is designed to prepare Ethereum for higher throughput by improving how blocks are built, processed and verified. Ethereum.org says BALs work like a map for the network, showing which parts of Ethereum’s database a block will access before execution begins.

The main Glamsterdam focus areas are:

• Parallel transaction processing
• Higher Layer 1 capacity
• Lower database-growth pressure
• More efficient block construction
• Stronger support for future scaling upgrades

Hegotá is expected to follow Glamsterdam. Buterin described Hegotá as likely Ethereum’s last major “pre-Lean” fork. After that, he expects future upgrades to carry a stronger Lean Ethereum design direction.

Privacy and Quantum Safety Move Up the Roadmap

One of the biggest changes in Buterin’s update is the priority given to privacy and quantum resistance. Privacy is no longer being treated as an optional add-on. Buterin said future designs for frames, mempools and state changes are now being evaluated with privacy-preserving transactions in mind. The strawmap also lists “private L1” as one of Ethereum’s long-term targets.

Quantum safety has also become more urgent. The roadmap points to post-quantum Layer 1 security as a long-term target, while Buterin said Ethereum researchers are working to replace quantum-vulnerable components with quantum-safe alternatives.

The roadmap’s quantum-safety work could affect several parts of Ethereum, including:

• Validator signatures
• Blob design
• Proof systems
• Long-term account security
• Consensus-layer cryptography

The shift does not mean quantum computers currently pose an immediate threat to Ethereum. It means core researchers are preparing for a future where today’s cryptographic assumptions may no longer be enough.

That same security-first approach appeared in Buterin’s recent writing on AI-assisted formal verification. He argued that AI tools could help developers write optimized code and machine-checkable proofs, especially for sensitive systems such as quantum-resistant signatures, STARK proof systems, consensus algorithms and EVM implementations.

State Changes Could Be the Most Disruptive Part

Buterin said the most disruptive part of the Lean Ethereum plan may be changes to Ethereum’s state, the stored data that accounts, balances and smart contracts depend on. Today’s Ethereum state is flexible, but that flexibility makes it harder to scale indefinitely. Buterin said the likely direction is to keep present-day “dynamic state” mostly unchanged while adding new, more restrictive types of state that can scale much further.

He gave a possible 2030 example:

• 2 TB of current-style dynamic state
• 100 TB of new-style scalable state

That change could matter for application developers. ERC-20 tokens, NFTs and many DeFi use cases may be able to move to newer state formats that reduce transaction costs. More complex contracts, including Uniswap-style liquidity pools and on-chain order books, may continue to rely on Ethereum’s existing state model. The goal is not to force every application to rewrite immediately. But the roadmap suggests some applications may become significantly cheaper if developers adopt new storage designs.

Ethereum May Need a New VM Layer

Buterin also said Ethereum will likely need a virtual machine beyond the EVM in some form. He mentioned leanISA and RISC-V as possible contenders, especially for recursive STARKs, programmable privacy and future scalability.

The long-term idea is that the EVM could become more of a developer-facing compiler target, while the protocol itself directly understands a lower-level VM such as RISC-V or leanISA. Buterin said that design remains far away.

For now, the important point is that Lean Ethereum is not only about higher gas limits or more blobs. It also involves deeper changes to how Ethereum verifies computation and structures execution.

Market Context Around Buterin’s Ethereum Activity

Buterin’s roadmap comments come months after renewed attention on wallet activity associated with vitalik.eth. Earlier on-chain coverage showed cumulative ETH sales from the wallet had exceeded a previously planned 16,384 ETH level, reaching about 19,318 ETH by late February.

That wallet activity drew market attention at the time, but it does not change the substance of the current roadmap discussion. The Lean Ethereum update is focused on protocol architecture, not short-term ETH price action or personal wallet movements.

Strawmap Is Still a Draft

The updated strawmap remains a coordination document, not a final schedule. Its maintainers describe it as a work-in-progress roadmap meant to help researchers, developers and governance participants think about Ethereum’s long-term Layer 1 direction.

That means timelines and features can still change. Ethereum upgrades typically move through research, client implementation, testing, community review and governance before reaching mainnet.

Still, Buterin’s message gives Ethereum’s next phase a clear direction. Lean Ethereum is focused on scaling the base layer, expanding rollup capacity, making privacy native, preparing for post-quantum security and simplifying parts of the protocol without breaking existing applications.