# Build on Testnet

## **HeLa Chain Developer Quickstart Guide**

If you have developed dApps on Ethereum or `any EVM compatible chain` before, you will feel at home. It is exactly the same. But if you are new, don’t worry, this document will help you embark on your first dApp development on HeLa chain.

> <mark style="color:$success;background-color:$success;">**Please, keep in mind we currently only support 0.8.9 solidity version.**</mark>&#x20;

### **Prerequisites**

1. **Remix IDE**

* Open this in your browser: [https://remix.ethereum.org](https://remix.ethereum.org/)<br>

2. **HeLa Testnet Wallet + Tokens**

* Use MetaMask or any EVM wallet.
* Add HeLa Testnet RPC:

  | Network name   | HeLa Testnet                                                                                |
  | -------------- | ------------------------------------------------------------------------------------------- |
  | RPC            | [https://testnet-rpc.helachain.com](https://testnet-rpc.helachain.com/)                     |
  | Chain ID       | 666888                                                                                      |
  | SYMBOL         | HLUSD                                                                                       |
  | Block Explorer | [https://testnet-blockexplorer.helachain.com](https://testnet-blockexplorer.helachain.com/) |
* Get test tokens from the Faucet To fund your wallet with transaction gas fee, go to HeLa Testnet Faucet. You will receive 10 HLUSD every 24 hours. <mark style="color:red;">Claim HLUSD Testnet Faucet:</mark> [https://testnet-faucet.helachain.com](https://testnet-faucet.helachain.com/)

3. **Switch MetaMask to HeLa Testnet**

### Step 1: Write the Smart Contract

We’ll start with a **Hello World Contract**.

1. Open Remix
2. Create a new file: `HelloHeLa.sol`
3. Paste this code:&#x20;

> <mark style="color:$success;">**Please, keep in mind we currently only support 0.8.9 solidity version.**</mark>&#x20;

```jsx
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

contract HelloHeLa {
    string public message;

    constructor(string memory _msg) {
        message = _msg;
    }

    function setMessage(string memory _msg) public {
        message = _msg;
    }

    function getMessage() public view returns (string memory) {
        return message;
    }
}

```

4. Save it.

### Step 2: Compile the Contract

1. In Remix, go to the **Solidity Compiler** tab
2. Click **Compile HelloHeLa.sol**
   * If no errors, you’re good to go.

### Step 3: Deploy to HeLa Testnet

1. Go to **Deploy & Run Transactions** tab
2. Change Environment to `Injected Provider - MetaMask` (it will auto-connect your wallet)
3. Make sure MetaMask is set to **HeLa Testnet**
4. Under Contract, select `HelloHeLa`
5. Add `"Hello from HeLa!"` in the constructor input
6. Click **Deploy**
7. Approve the transaction in MetaMask

**Your contract is now live on HeLa Testnet!**

### Step 4: Interact with Your Contract

1. After deploying, Remix will show a panel with your contract.
2. Click `getMessage` — it should return `"Hello from HeLa!"`
3. Try `setMessage("Welcome to HeLa")`
4. Call `getMessage` again to see the updated message.

### Step 5: Verify on HeLa Explorer (Optional)

1. Copy your contract address from Remix
2. Open <https://testnet-blockexplorer.helachain.com/>

Transaction and smart contracts can be observed and verfied in Testnet Block Explorer.

3. Paste the address and see your live contract

Build more, explore contracts, and join the [<mark style="color:$primary;">HeLa Developer Discord</mark>](https://discord.gg/NEBtTztJCj) for help and ideas!