eth_chainId on Avalanche
Everything below was measured on 2026-10-13 by calling eth_chainId on Avalanche 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.
Avalanche 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 Avalanche 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 43114; every mainstream library does this by default.
| eth_chainId | 0xa86a (43,114) |
|---|---|
| net_version | 43114 |
Example request
curl -s https://rpc.swiftnodes.io/rpc/avalanche?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 Avalanche before signing
import { createPublicClient, http } from "viem";
const client = createPublicClient({
transport: http("https://rpc.swiftnodes.io/rpc/avalanche?key=YOUR_API_KEY"),
});
const id = await client.getChainId(); // 43114
if (id !== 43114) throw new Error(`wrong chain: ${id}`);
// Add Avalanche to a browser wallet
await window.ethereum.request({
method: "wallet_addEthereumChain",
params: [{
chainId: "0xa86a",
chainName: "Avalanche",
nativeCurrency: { name: "AVAX", symbol: "AVAX", decimals: 18 },
rpcUrls: ["https://rpc.swiftnodes.io/rpc/avalanche?key=YOUR_API_KEY"],
}],
});Other methods on Avalanche
- eth_blockNumberSupported
- eth_getBalanceSupported
- eth_getBlockByNumberSupported
- eth_getTransactionByHashSupported
- eth_getTransactionReceiptSupported
- eth_callSupported
- eth_estimateGasSupported
- eth_gasPriceSupported
- eth_maxPriorityFeePerGasSupported
- eth_sendRawTransactionSupported
- eth_getTransactionCountSupported
- eth_getCodeSupported
- eth_subscribeSupported
- eth_getLogsSupported
- eth_getBlockReceiptsSupported
- eth_feeHistorySupported
- eth_getProofSupported
- eth_createAccessListSupported
- debug_traceCallSupported
- trace_blockNot available
- trace_transactionNot available
eth_chainId on other chains
- Ethereum
- Base
- Arbitrum
- Optimism
- Polygon
- BNB Smart Chain
- Sonic
- Linea
- Scroll
- zkSync Era
- Blast
- Mantle
- Gnosis
- Celo
- Berachain
- Monad
- Unichain
- Kaia
- PulseChain
- World Chain
- Ronin
- Abstract
- ApeChain
- MegaETH
- Fantom
- Lisk
- Hemi
- X Layer
- BOB
- Plasma
- Fraxtal
- Zora
- Story
- Soneium
- Sei
- Hyperliquid
- Taiko
- Morph
- Ink
- Katana
- Ethereum Classic
- opBNB
- Mode
- Flare
- Core
- Chiliz
- Telos EVM
- Tempo
- Cronos
- Manta Pacific
- Shibarium
- Boba Network
- Arbitrum Nova
- Immutable zkEVM
Frequently asked questions
Does Avalanche support eth_chainId?
Yes. eth_chainId answered on the SwiftNodes Avalanche endpoint when our weekly probe called it through the customer path (2026-10-13).
What is the Avalanche chain ID?
43114 in decimal, 0xa86a in hex, as returned by eth_chainId on 2026-10-13.
How do I add Avalanche to MetaMask?
Call wallet_addEthereumChain with chainId 0xa86a, the native currency AVAX with 18 decimals, and your RPC URL; the example on this page has the full object.
Avalanche endpoints, live block height and WebSocket status are on the Avalanche RPC page.
One key covers every chain we serve, and SwiftNodes has a free tier.