beacon-kit

Berachain's Consensus Client

What is BeaconKit?

BeaconKit is Berachain’s consensus client. It implements the Ethereum consensus layer specification with Berachain-specific modifications, using a modified CometBFT for consensus instead of Ethereum’s standard beacon chain consensus.

Berachain is a high-performance L1 blockchain powered by Proof of Liquidity (PoL), an incentive mechanism that aligns validators, protocols, and users through its three-token system (BERA, BGT, HONEY).

BeaconKit communicates with Bera-Reth (the execution client) via the standard Engine API, forming the two-client architecture used by Berachain nodes.

Key Differences from Ethereum

• CometBFT Consensus — Uses timeout-based rounds instead of fixed 12-second slots. If a proposer fails, a new round starts at the same height with a different proposer.
• Single-Slot Finality — Blocks are finalized immediately when 2/3+ validators commit, unlike Ethereum’s ~13-minute finalization through Casper FFG checkpoints.
• No Missed Slots — Block heights are strictly sequential with no gaps. Every height eventually produces a block through round-based consensus.
• No Attestations or Committees — Consensus is driven by CometBFT’s validator voting (prevotes/precommits) rather than Ethereum’s attestation committees and sync committees.
• Capped Validator Set — The active validator set is capped (currently 69 validators) rather than being open-ended.
• EVM Inflation Withdrawal — Every block includes a mandatory EVM inflation withdrawal as its first withdrawal, a Berachain-specific economic mechanism.

Networks

Network	Chain ID	Description
Mainnet	80094	Production network
Bepolia	80069	Public testnet
Devnet	80087	Local development

Network configurations are stored in testing/networks/<chain-id>/.

Execution Client

BeaconKit requires Bera-Reth, a Berachain-specific fork of Reth. Communication happens over the Engine API with JWT authentication.

Quick Start

Prerequisites

• Docker
• Golang
• Foundry

Open two terminals side by side.

Terminal 1 — Start the consensus client:

make start

Terminal 2 — Start the execution client (after beacond is running, since make start generates the execution genesis file):

make start-reth

The devnet runs with chain ID 80087. The following dev account is preloaded with the native token:

Address:     0x20f33ce90a13a4b5e7697e3544c3083b8f8a51d4
Private Key: 0xfffdbb37105441e14b0ee6330d855d8504ff39e705c3afa8f859ac9865f99306

Multinode Devnet (Kurtosis)

For running a multinode local devnet using Kurtosis:

make start-devnet

See the Kurtosis README for full details on configuration and usage.

Project Structure

beacon/              Core beacon chain logic (blockchain service, validator service)
chain/               Chain specifications and network configs
cli/                 CLI commands and configuration
config/              Configuration templates (TOML)
consensus-types/     Consensus layer types (blocks, states, validators, SSZ)
contracts/           Solidity contracts (deposit contract, staking)
da/                  Data availability (blob management, KZG commitments)
engine-primitives/   Execution engine types (Engine API types, payloads)
execution/           Execution client integration (Engine API client, deposit syncing)
kurtosis/            Kurtosis multinode devnet deployment
node-api/            REST API implementation (beacon API handlers)
node-core/           Core infrastructure (dependency injection, service registry)
primitives/          Basic types and constants (Slot, Gwei, ValidatorIndex)
state-transition/    State transition logic (state machine, fork transitions)
storage/             Database backends (block store, blob store, beacon DB)
testing/             Test utilities, network configs, e2e and simulation tests

Development

Building

make build                # Build beacond binary to build/bin/beacond
make install              # Install beacond to $GOPATH/bin
make build-docker         # Build Docker image

Testing

make test                 # Run all tests (unit + forge)
make test-unit            # Run unit tests with coverage
make test-unit-bench      # Run benchmarks
make test-unit-fuzz       # Run Go fuzz tests
make test-simulated       # Run simulation tests
make test-e2e             # Run e2e tests (builds Docker image first)
make test-forge-cover     # Run Solidity tests with coverage

Linting & Formatting

make lint                 # Run all linters
make format               # Run all formatters
make golangci-fix         # Auto-fix Go linting issues
make gosec                # Run security scanner
make nilaway              # Run nil pointer checker
make vulncheck            # Run govulncheck vulnerability scanner

Code Generation

make generate             # Run all code generation
make proto                # Generate protobuf code
make generate-check       # Verify generated code is up to date

Documentation

• Berachain Docs — Official documentation
• What is BeaconKit — Conceptual overview
• Node Quickstart — Deploy a mainnet or testnet node
• Docker Devnet Guide — Run a devnet with Docker
• Kurtosis Guide — Multinode deployment with Kurtosis
• Kurtosis README — Local Kurtosis configuration and usage

License

BeaconKit is licensed under BUSL-1.1.