Add Ferminux to Your Wallet

One-tap (MetaMask and compatible wallets)

Any dapp (the Ferminux site does this) can prompt the wallet with a single wallet_addEthereumChain request — the canonical payload lives at wallet/metamask-add-network.json:

{
  "method": "wallet_addEthereumChain",
  "params": [
    {
      "chainId": "0xF79",
      "chainName": "Ferminux Network",
      "nativeCurrency": { "name": "Ferminux", "symbol": "FMX", "decimals": 18 },
      "rpcUrls": ["https://rpc.ferminux.net"],
      "blockExplorerUrls": ["https://explorer.ferminux.net"]
    }
  ]
}

From a dapp's JavaScript:

await window.ethereum.request({
  method: "wallet_addEthereumChain",
  params: [{
    chainId: "0xF79",
    chainName: "Ferminux Network",
    nativeCurrency: { name: "Ferminux", symbol: "FMX", decimals: 18 },
    rpcUrls: ["https://rpc.ferminux.net"],
    blockExplorerUrls: ["https://explorer.ferminux.net"]
  }]
});

Manual entry

MetaMask → Settings → Networks → Add a network manually:

For a local node or devnet, use RPC URL http://localhost:8545 with the same Chain ID 3961.

Common issues

"Chain ID returned by the custom network does not match the submitted chain ID" You typed the wrong chain ID, or the RPC URL points at a different network. Ferminux is decimal 3961 (hex 0xF79 — same number, two notations; MetaMask's manual form takes the decimal). Verify what the endpoint actually reports:

curl -s -X POST -H 'Content-Type: application/json' \
  --data '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}' \
  https://rpc.ferminux.net
# → {"jsonrpc":"2.0","id":1,"result":"0xf79"}

"Could not fetch chain ID. Is your RPC URL correct?" The RPC endpoint is unreachable from your machine. For a local node: is it running, and did you start it with --http? For the public endpoint: check your connection / firewall. Run the curl above to see the raw failure.

Gas estimate / base fee looks strange. Ferminux runs EIP-1559 from genesis, so wallets show a base fee + priority fee, not a single legacy gas price. The base fee started at 1 gwei and decays toward the protocol floor while blocks are not full — so seeing a base fee of a few wei on a quiet chain is correct, not a display bug. A simple transfer costs 21,000 gas; at 1 gwei that is 0.000021 FMX. If your wallet suggests a huge priority tip out of habit (some default to 1.5 gwei), you can lower it — almost any tip gets you in the next block on an uncongested chain.

"This currency symbol doesn't match the network's..." — MetaMask sometimes warns about symbols for chains missing from its internal list. Ferminux is a sovereign chain; FMX with 18 decimals is correct. Accept and continue.

Token shows 0 balance after adding. FMX is the native coin — do not add it as a custom token. Custom tokens are for on-chain ERC-20s such as AZNT (6 decimals) or TokenFactory launches; for those, use "Import tokens" with the contract address from the explorer.

Hardware wallets / clef: signing tools that default to Ethereum mainnet (chain-id 1) will produce invalid signatures. Anything EIP-155 aware must be told chain-id 3961 (clef users: --chainid 3961).