web3_clientVersion

web3_clientVersion returns a free-form string identifying the client software running the node — for example a Geth-style string, or an Arbitrum Nitro build identifier. On Arbitrum One (chain ID 42161), the Optimistic Rollup that settles to Ethereum and pays gas in ETH, the canonical node software is Nitro (running an ArbOS execution layer), so the value you read from https://arbitrum.therpc.io/YOUR_API_KEY reflects that stack rather than a vanilla Ethereum L1 client. The method takes no parameters and is handy for diagnostics, logging, and confirming which implementation is answering your calls.

Use cases

• Detect the underlying client type and version of an Arbitrum One node to enable or disable client-specific behaviour — for instance toggling namespace-dependent calls based on whether you are talking to a Nitro build.
• Log node identity during infrastructure diagnostics so you can correlate odd RPC behaviour on Arbitrum One with a specific client version across your fleet.

Parameters

This method takes no parameters. Pass an empty array [].

Response

Example request

1curl https://arbitrum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "web3_clientVersion",
7    "params": [],
8    "id": 1
9  }'

Try it live in the Arbitrum One playground.

Errors & troubleshooting

Common pitfalls

• Managed RPC providers often return a custom, normalised, or redacted string rather than the exact upstream client version, so do not assume the text reveals the precise build serving your Arbitrum One traffic.
• Do not gate production logic on parsing this string. Client banners change format and providers rewrite them; test for the actual method or namespace availability you need directly instead of inferring it from the version text.

Supported networks

• Mainnet — Chain ID: 42161
• Sepolia — Chain ID: 421614

See also

• net_version

1curl https://arbitrum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"web3_clientVersion","params":[]}'