eth_chainId

The eth_chainId method returns the chain ID of the current network. The chain ID is a unique identifier for different Arbitrum networks (42161 for Arbitrum One mainnet, 421614 for Arbitrum Sepolia testnet) and is crucial for preventing replay attacks across different networks.

This method is essential for wallet applications and transaction signing to ensure transactions are executed on the intended network. By including the chain ID in the transaction signature (as defined in EIP-155), transactions signed for one network cannot be replayed on another network, protecting users from cross-chain replay attacks. Applications should verify the chain ID matches their expected network before signing or broadcasting transactions.


Parameters

This method does not require any parameters.

Return Object
field
type
description
result
string
The chain ID encoded as a hexadecimal string. For Arbitrum networks: 0xa4b1 (42161) for Arbitrum One mainnet, 0x66eee (421614) for Arbitrum Sepolia testnet.
Request Example
Request
Response Example
Response

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