The eth_chainId method returns the chain ID of the current network. The chain ID is a unique identifier for different Optimism networks (10 for OP Mainnet, 11155420 for OP Sepolia) 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. Common values include: 0xa (10) for Optimism mainnet, 0xaa37dc (11155420) for OP Sepolia testnet.

Request Example

Request

Response Example

Response

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