What Are Ethereum Clients?
Ethereum clients are software applications that implement the Ethereum protocol, enabling communication across a peer-to-peer network. After the Proof-of-Stake (PoS) upgrade, each node requires two interdependent client types:
Execution Client (EL Client / Execution Engine):
- Listens for new transactions
- Executes transactions in the Ethereum Virtual Machine (EVM)
- Maintains Ethereum's state and database
- Handles the execution layer protocol
Consensus Client (CL Client / Beacon Node):
- Implements PoS consensus algorithms
- Coordinates network agreement on validated data
- Optional "validator" software enables active network participation
These clients work in tandem (see diagram below) to track chain head progression and facilitate user-network interactions.
👉 Explore how clients synchronize
The Importance of Client Diversity
Multiple independent implementations in different programming languages create Ethereum's unique resilience against attacks and single points of failure. All compliant clients adhere to these core specifications:
- Original Ethereum Yellow Paper
- Execution Specifications
- Consensus Specifications
- Implemented EIPs through network upgrades
Execution Client Landscape
| Client | Language | OS Support | Networks | Sync Modes | State Storage |
|---|---|---|---|---|---|
| Geth | Go | Linux, Windows, macOS | Mainnet, Sepolia, Goerli | Snap, Full | Archive, Pruned |
| Nethermind | C#/.NET | Cross-platform | Mainnet + testnets | Snap (no service), Fast, Full | Archive, Pruned |
| Besu | Java | Cross-platform | Extensive testnet support | Snap, Fast, Full | Archive, Pruned |
| Erigon | Go | Cross-platform | Multiple networks | Full | Archive, Pruned |
| Reth | Rust | Cross-platform | Mainnet + testnets | Full | Archive, Pruned |
👉 Compare network support details
Consensus Client Options
- Lighthouse (Rust)
- Lodestar (TypeScript)
- Nimbus (Nim)
- Teku (Java)
- Prysm (Go)
Each offers unique advantages in resource efficiency, configuration flexibility, or enterprise features.
FAQ: Ethereum Client Essentials
Why run multiple client implementations?
Distributing node software across different codebases minimizes systemic risks from bugs or vulnerabilities in any single implementation.
How do execution and consensus clients communicate?
Through the Engine API using standardized JSON-RPC methods for secure data exchange between layers.
What's the minimum hardware requirement?
Requirements vary by client, but generally:
- Execution client: 4+ core CPU, 16GB RAM, 1TB+ SSD
- Consensus client: 2+ core CPU, 8GB RAM
Can I switch clients without losing stake?
Yes, validators can migrate between consensus clients after proper configuration transitions.
How often do clients receive updates?
Teams typically release patches weekly, with major upgrades aligned to network hard forks.