Developer Environment Setup

RPC Endpoints

Network	Chain ID	HTTP RPC	WebSocket RPC	Status
Nexus Mainnet	3946	https://mainnet.rpc.nexus.xyz	wss://mainnet.rpc.nexus.xyz	Live
Nexus Testnet	3945	https://testnet.rpc.nexus.xyz	wss://testnet.rpc.nexus.xyz	Live

Notes:

• WebSocket connections require an X-Api-Key header on the upgrade handshake. Since browsers cannot set custom headers on WebSocket connections, WSS is currently limited to server-side use (Node.js, Python, etc). Browser dApps should use HTTP polling or a server-side relay.

• OFAC-restricted jurisdictions are blocked at the edge. See Restricted Jurisdictions.

Request Limits

Limit	Value	Error
Max payload size	2 MB	JSON-RPC -32005
Max batch sub-requests	10	JSON-RPC -32005
Per-IP rate limiting	Active	JSON-RPC error + Retry-After header

Testnet Faucet

Developers can acquire Testnet $NEX here: https://faucet.nexus.xyz

Wallet Setup

Field	Mainnet	Testnet
Network Name	Nexus Mainnet	Nexus Testnet
RPC URL	https://mainnet.rpc.nexus.xyz	https://testnet.rpc.nexus.xyz
Chain ID	3946	3945
Currency Symbol	NEX	NEX
Block Explorer URL	https://explorer.nexus.xyz	https://testnet.explorer.nexus.xyz

To add programmatically:

await window.ethereum.request({
  method: "wallet_addEthereumChain",
  params: [{
    chainId: "0xF6A",  // 3946 in hex
    chainName: "Nexus Mainnet",
    nativeCurrency: {
      name: "NEX",
      symbol: "NEX",
      decimals: 18,
    },
    rpcUrls: ["https://mainnet.rpc.nexus.xyz"],
    blockExplorerUrls: ["https://explorer.nexus.xyz"],
  }],
});

Hardhat

npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox

hardhat.config.ts:

import { HardhatUserConfig } from "hardhat/config";
import "@nomicfoundation/hardhat-toolbox";

const config: HardhatUserConfig = {
  solidity: "0.8.24",
  networks: {
    nexusMainnet: {
      url: process.env.NEXUS_RPC_URL || "https://mainnet.rpc.nexus.xyz",
      chainId: 3946,
      accounts: process.env.PRIVATE_KEY ? [process.env.PRIVATE_KEY] : [],
    },
    nexusTestnet: {
      url: process.env.NEXUS_TESTNET_RPC_URL || "https://testnet.rpc.nexus.xyz",
      chainId: 3945,
      accounts: process.env.PRIVATE_KEY ? [process.env.PRIVATE_KEY] : [],
    },
  },
};

export default config;

Foundry

curl -L https://foundry.paradigm.xyz | bash
foundryup

foundry.toml:

[profile.default]
solc_version = "0.8.24"

[rpc_endpoints]
nexus_mainnet = "https://mainnet.rpc.nexus.xyz"
nexus_testnet = "https://testnet.rpc.nexus.xyz"

forge create src/MyContract.sol:MyContract \
  --rpc-url nexus_testnet \
  --chain-id 3945 \
  --private-key $PRIVATE_KEY

Remix

1. Open Remix IDE

2. Deploy & Run tab → "Injected Provider — MetaMask"

3. Ensure MetaMask is connected to Nexus (chain ID 3946 or 3945)

Environment verification

curl -s -X POST https://mainnet.rpc.nexus.xyz \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'

Expected: a valid hex block number in the result field.

curl -s -X POST https://mainnet.rpc.nexus.xyz \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}'

Expected: "0xf6a" (3946) for mainnet, "0xf69" (3945) for testnet.