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RPC method

eth_chainId on Hemi

Supported on SwiftNodes

Everything below was measured on 2026-10-13 by calling eth_chainId on Hemi through the same endpoint customers use, and is re-measured weekly.

What eth_chainId does

Returns the chain ID (EIP-155) as a hex string. Wallets and libraries check it before signing, and the signature commits to it, so a transaction signed for one chain cannot be replayed on another.

Hemi chain ID, as measured

net_version returns the same number as decimal text. Older tools read net_version; use eth_chainId, which is the value signatures commit to.

We sent Hemi a legacy transaction signed without a chain ID (pre-EIP-155). Its nodes refused it: "only replay-protected (EIP-155) transactions allowed over RPC". Sign with chain ID 43111; every mainstream library does this by default.

eth_chainId0xa867 (43,111)
net_version43111

Example request

curl -s https://rpc.swiftnodes.io/rpc/hemi?key=YOUR_API_KEY \
  -X POST -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_chainId","params":[]}'
// Check you are on Hemi before signing
import { createPublicClient, http } from "viem";

const client = createPublicClient({
  transport: http("https://rpc.swiftnodes.io/rpc/hemi?key=YOUR_API_KEY"),
});

const id = await client.getChainId(); // 43111
if (id !== 43111) throw new Error(`wrong chain: ${id}`);

// Add Hemi to a browser wallet
await window.ethereum.request({
  method: "wallet_addEthereumChain",
  params: [{
    chainId: "0xa867",
    chainName: "Hemi",
    nativeCurrency: { name: "ETH", symbol: "ETH", decimals: 18 },
    rpcUrls: ["https://rpc.swiftnodes.io/rpc/hemi?key=YOUR_API_KEY"],
  }],
});

Other methods on Hemi

eth_chainId on other chains

Frequently asked questions

Does Hemi support eth_chainId?

Yes. eth_chainId answered on the SwiftNodes Hemi endpoint when our weekly probe called it through the customer path (2026-10-13).

What is the Hemi chain ID?

43111 in decimal, 0xa867 in hex, as returned by eth_chainId on 2026-10-13.

How do I add Hemi to MetaMask?

Call wallet_addEthereumChain with chainId 0xa867, the native currency ETH with 18 decimals, and your RPC URL; the example on this page has the full object.

Hemi endpoints, live block height and WebSocket status are on the Hemi RPC page.

One key covers every chain we serve, and SwiftNodes has a free tier.