> For the complete documentation index, see [llms.txt](https://docs.nexus.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexus.xyz/network/building-on-nexus/developer-environment-setup.md).

# Developer Environment Setup

### RPC Endpoints

<table><thead><tr><th>Network</th><th width="86.41796875">Chain ID</th><th width="276">HTTP RPC</th><th width="150.3046875">WebSocket RPC</th><th width="94.90234375">Status</th></tr></thead><tbody><tr><td>Nexus Mainnet </td><td>3946</td><td><code>https://mainnet.rpc.nexus.xyz</code></td><td><code>wss://mainnet.rpc.nexus.xyz</code></td><td>Live</td></tr><tr><td>Nexus Testnet</td><td>3945</td><td><code>https://testnet.rpc.nexus.xyz</code></td><td><code>wss://testnet.rpc.nexus.xyz</code></td><td>Live</td></tr></tbody></table>

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](https://nexus.xyz/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:

```javascript
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

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

`hardhat.config.ts`:

```typescript
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

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

`foundry.toml`:

```toml
[profile.default]
solc_version = "0.8.24"

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

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

### Remix

1. Open [Remix IDE](https://remix.ethereum.org/)
2. Deploy & Run tab → "Injected Provider — MetaMask"
3. Ensure MetaMask is connected to Nexus (chain ID 3946 or 3945)

### Environment verification

```bash
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.

```bash
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.


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