What is a chain ID?

Lots of networks run the same EVM and share one address format, so they need a way to tell each other apart. That is the chain ID. Ethereum mainnet is 1, OP Mainnet is 10, Base is 8453, Arbitrum One is 42161 and HyperEVM is 999.

EIP-155, live on Ethereum since November 2016, put the chain ID inside the transaction signature. A transaction signed for Base commits to 8453 and is rejected everywhere else. Before that, replays were real. After Ethereum and Ethereum Classic split in 2016, a transaction on one chain could be copied onto the other.

Many wallets and sites such as chainlist.org pull names, IDs and RPC URLs from the community-run ethereum-lists registry. Scam networks sometimes reuse a familiar name with a different ID or a hostile RPC, so check the number when you add a network by hand. Solana has no numeric chain ID; its clusters are told apart by genesis hash.

When a dapp asks your wallet to switch to chain 8453, the wallet recognizes it as Base and asks you to approve the switch. Had the request named an ID the wallet had never seen, under a familiar-sounding name, a careful wallet would warn you first.

Also called: chainId, network ID.

Cashboard's registry has 15 networks, including Ethereum, Base, Arbitrum One and HyperEVM. Chain status, Portfolio and Trending on-chain each read the networks you pick. If you connect a browser wallet to pick an address, the Portfolio widget reads the wallet's chain ID and, if Cashboard knows that network, switches to it. Connecting only shares the address, never a signature.

• Chain status
• Portfolio
• Trending on-chain

• Official documentationeips.ethereum.org

• EVM
• RPC endpoint
• Layer 2
• Connect wallet