eth_chainId

eth_chainId returns the EIP-155 chain ID of the network the endpoint is serving. For the Avalanche C-Chain — the EVM chain where gas is paid in AVAX — that value is 43114, returned as the hex string "0xa86a". Calling https://avalanche.therpc.io/YOUR_API_KEY should always echo "0xa86a"; this is the identifier wallets and signers fold into the EIP-155 signature so an AVAX transaction can never be replayed on Ethereum, BSC, or any other EVM network.

Use cases

• Pre-flight check before signing or submitting — confirm the wallet is on chain ID 43114 and not pointed at Fuji testnet or another EVM network.
• Combine with eth_blockNumber for a full "alive and on the right chain" probe of your Avalanche C-Chain endpoint.
• Select the correct contract address for a multi-chain deployment, e.g. pick the C-Chain GMX or Aave address when the response is "0xa86a".
• Guard against cross-chain replay: the chain ID baked into EIP-155 signatures stops an AVAX-signed transaction from being valid elsewhere.

Parameters

Diese Methode erwartet keine Parameter. Übergib ein leeres Array [].

Response

Example request

1curl https://avalanche.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_chainId",
7    "params": [],
8    "id": 1
9  }'

Try it live in the Avalanche playground.

Errors & troubleshooting

Common pitfalls

• Do not confuse this with net_version, which returns a network ID as a decimal string; on the Avalanche C-Chain both happen to be 43114, but treating them as interchangeable is a portability bug.
• The result is the hex string "0xa86a" — compare with BigInt(result) === 43114n rather than string-matching, so casing or zero-padding differences never cause a false mismatch.

Supported networks

• Mainnet — Chain ID: 43114
• Fuji

See also

• eth_blockNumber
• net_version

1curl https://avalanche.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_chainId","params":[]}'