Lean Ethereum

A visionary Ethereum Foundation initiative unveiled in July 2025 to harden and scale the Ethereum protocol through minimalism, formal verification, and hash-based post-quantum cryptography.

What is Lean Ethereum?

Lean Ethereum is a comprehensive upgrade blueprint for the Ethereum protocol, announced on July 31, 2025, by the Ethereum Foundation to mark Ethereum’s 10th anniversary.

It reimagines the consensus (CL), data (DL), and execution (EL) layers from first principles, emphasizing “fort mode” for unbreakable security—achieving 100% uptime against threats like quantum attacks and nation-state adversaries—and “beast mode” for extreme scalability. Concrete targets include 1 gigagas per second on Layer 1 (equivalent to 10,000 transactions per second) and 1 teragas per second on Layer 2 (10 million TPS), all while preserving decentralization and EVM compatibility. The design philosophy prioritizes minimalism, modularity, and encapsulated complexity, enabling full chain verification directly in browsers, wallets, and mobile devices without trusting intermediaries.

Key components include Lean Consensus (formerly “Beam Chain”), a hardened beacon chain with finality in seconds using hash-based aggregate signatures for post-quantum security; Lean Data (Blobs 2.0), featuring granular post-quantum blob sizing for calldata-like developer experiences and data availability sampling (DAS) commitments; and Lean Execution (EVM 2.0), a SNARK-friendly minimal instruction set potentially based on RISC-V, which boosts performance via real-time zkVMs while maintaining backward compatibility with existing Ethereum network effects.