web3_clientVersion | Optimism RPC Docs

Get the client software version of your Optimism node. Essential for compatibility checks, fleet monitoring, and debugging client-specific behavior.

Returns the current client software version string for your Optimism node, including the client name, version number, OS, and runtime.

Why Optimism? Build on the heart of the Superchain powering 60%+ of Ethereum L2 transactions with $6B+ TVL with OP Stack modularity, Superchain interoperability, 17M+ daily transactions across 33 chains, and 20% of tokens for public goods.

When to Use This Method

web3_clientVersion is valuable for L2 builders, DeFi developers, and teams launching Superchain-compatible apps:

Client Compatibility Checks — Verify the node runs a client version that supports the RPC methods your application needs
Fleet Version Monitoring — Track client versions across a multi-node infrastructure to coordinate upgrades
Debugging Client-Specific Behavior — Identify which client (Geth, Erigon, Nethermind, Besu, etc.) is serving requests when behavior differs
Security Auditing — Detect nodes running outdated versions with known vulnerabilities

Code Examples

Common Use Cases

1. Client Version Parser

Parse the version string to extract structured information:

JavaScript

function parseClientVersion(versionString) {
  const parts = versionString.split('/');

  return {
    client: parts[0],
    version: parts[1] || 'unknown',
    os: parts[2] || 'unknown',
    runtime: parts[3] || 'unknown'
  };
}

async function getNodeInfo(provider) {
  const version = await provider.send('web3_clientVersion', []);
  const parsed = parseClientVersion(version);

  console.log(`Client: ${parsed.client}`);
  console.log(`Version: ${parsed.version}`);
  console.log(`OS: ${parsed.os}`);
  console.log(`Runtime: ${parsed.runtime}`);

  return parsed;
}

2. Fleet Version Audit

Check all nodes in a fleet and report version inconsistencies:

Python

import requests

def audit_fleet_versions(endpoints):
    versions = {}
    for endpoint in endpoints:
        try:
            response = requests.post(
                endpoint,
                json={'jsonrpc': '2.0', 'method': 'web3_clientVersion', 'params': [], 'id': 1},
                timeout=5
            )
            version = response.json()['result']
            versions[endpoint] = version
        except Exception as e:
            versions[endpoint] = f'ERROR: {e}'

    # Group by client version
    grouped = {}
    for endpoint, version in versions.items():
        grouped.setdefault(version, []).append(endpoint)

    for version, nodes in grouped.items():
        print(f'{version}: {len(nodes)} node(s)')

    if len(grouped) > 1:
        print('WARNING: Inconsistent versions detected across fleet')

    return versions

3. Feature Detection by Client

Adjust RPC behavior based on the detected client type: