ethlambda · R&D Progress
· Lean Consensus Client

Minimalist.
Fast.
Modular.

ethlambda is a minimalist, fast, and modular implementation of the Lean Ethereum consensus client, built by LambdaClass with deep expertise in distributed systems and blockchain infrastructure.

Open source · MIT license · Built and maintained by LambdaClass

Get started → Documentation Live Metrics ↗
Current devnet pq-devnet-5
Working on pq-devnet-6
License MIT
~/ethlambda · zsh
$ make run-devnet
→ cloning lean-quickstart… ok
→ building docker image… ok
→ generating genesis files… ok
→ starting all clients… ok
$ ethlambda --is-aggregator
peers · 4  ·  block #00047021
attestations aggregated  ·  finalized
1024
Validators in a single devnet Largest validator set run to date, on pq-devnet-5.

Project Highlights

Why ethlambda
Full Lean Consensus Compatibility

A cutting-edge consensus client for the next iteration of the Beacon Chain: the Lean Chain.

Built by Experts

Developed by LambdaClass, the team behind ethrex 🦖, the production-ready Ethereum execution client.

Minimalist by Design

Less than 10k lines of Lean code with low abstraction: easy to maintain, read, and audit.

Community-Driven

Fully open-source, with an active dev team and contributions welcome.

Current Status

PQ Interop · Devnet Progress
History
Oct 2025

pq-devnet-0 Completed

Goals
  • Create leanSpec framework
  • Multi-client coordination (no PQ sigs yet)
  • Interop trials: 4s slots, QUIC, Gossipsub v1.0
  • Apply modified 3SF-mini consensus mechanism
Dec 2025

pq-devnet-1 Completed

Goals
  • Integrate leanSig signing & verification
  • Apply basic signature aggregation (by concatenation)
  • Baseline performance metrics for PQ signing & verification
Specification
Jan 2026

pq-devnet-2 Completed

Goals
  • Integrate leanMultisig aggregation
  • Baseline performance metrics for PQ signature aggregation
Specification Docker: devnet2
Feb 2026

pq-devnet-3 Completed

Goals
  • Decouple aggregation from block production via separate aggregator role
  • Establish protocol for propagating aggregated signatures
  • Create foundation for different aggregation/propagation strategies
Specification Docker: devnet3
Jun 2026

pq-devnet-4 Completed

Goals
  • Enable recursive PQ signature aggregation using leanVm
  • Coalesce multiple aggregates for the same message into one final aggregate
  • Ensure blocks contain a single aggregate per message
Specification Docker: devnet4
Active

pq-devnet-5 Active

Goals
  • Produce one block-level aggregation proof covering multiple attestation messages
  • Leverage proof decomposability so per-message proofs remain recoverable
Tracking issue Docker: devnet5 Live Metrics ↗
Planning

pq-devnet-6 Planning

Goals
  • To be defined

Read More

Documentation · Blog
Documentation

ethlambda Docs

Full technical documentation covering setup, configuration, devnet integration, metrics, and the client's internal architecture.

docs.ethlambda.xyz ↗
Blog Post

Building a Post-Quantum Ethereum Client with the Help of Shared Tooling

How ethlambda leverages shared tooling across the Lean Ethereum ecosystem to accelerate post-quantum client development.

blog.lambdaclass.com ↗
Blog Post

Building a Minimalist Post-Quantum Ethereum Client: ethlambda's Architecture

A deep dive into the architectural decisions behind ethlambda: why minimalism matters and how the codebase is structured for clarity and performance.

blog.lambdaclass.com ↗
GitHub

Source Code & Contributing

Explore the codebase, open issues, submit pull requests, or read CONTRIBUTING.md to get involved with ethlambda's development.

github.com/lambdaclass/ethlambda ↗

Follow Us

Community · Social
Telegram

ethlambda Telegram Group

Daily development updates and a place to ask questions or chat about anything Lean-related. The weekly community call link is posted here every Friday before the stream on @class_lambda.

t.me/ethlambda_client ↗
X / Twitter

Follow @ethlambda_lean

Occasional updates on devnet milestones, releases, and what the team is shipping next on the road to a post-quantum Ethereum.

x.com/ethlambda_lean ↗