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Prerequisites

Ensure that you have a recent version of NodeJs installed. You can check this using the following command: 
node -v
This guide was written using the following version: 
v22.16.0
If you do not have NodeJs installed yet, do so using: You will need a wallet, and an account that has been funded with some Testnet INJ.
You can request EVM testnet funds from the Injective Testnet faucet.
After creating your account, be sure to copy your private key somewhere accessible, as you will need it to complete this tutorial.
Note that private keys should be handled with caution. The instructions here should be considered sufficient for local development and Testnet. However, these are not secure enough for private keys used on Mainnet. Please ensure that you follow best practices for key security on Mainnet, and do not re-use the same keys/ accounts between Mainnet and other networks.

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Set up a new Hardhat project

Use git to clone the demo repo, which already has the project completely set up for you. 
git clone https://github.com/injective-dev/hardhat-inj
Install dependencies from npm: 
npm install

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Orientation

While waiting for npm to download and install, open the repo in your code editor/ IDE, and take a look at the directory structure. 
hardhat-inj/
  contracts/
    Counter.sol → smart contract Solidity code
  script/
    deploy.js → deployment script
  test/
    Counter.test.js → test cases
  hardhat.config.js → configuration
  .example.env
The hardhat.config.js file is already pre-configured to connect to the Injective EVM Testnet. All you need to do before proceeding is to provide it with a private key of your Injective Testnet account. 
cp .example.env .env
Edit the .env file to add the private key. Optionally, you may wish to update to any alternative JSON-RPC endpoints. 
PRIVATE_KEY=your private key without 0x prefix
INJ_TESTNET_RPC_URL=https://k8s.testnet.json-rpc.injective.network/

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Edit the smart contract

The smart contract that is included in this demo is very basic. It:
  • Stores one value which is a number.
  • Exposes a value() query method.
  • Exposes an increment(num) transaction method.
Open the file: contracts/Counter.sol 
// SPDX-License-Identifier: MIT
pragma solidity 0.8.28;

contract Counter {
    uint256 public value = 0;

    function increment(uint256 num) external {
        value += num;
    }
}

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Compile the smart contract

Run the following command: 
npx hardhat compile
Hardhat will automatically download and run the version of the Solidity compiler (solc) that was configured in the hardhat.config.js file.

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Check the compilation output

After the compiler completes, you should see additional directories in the project directory: 
hardhat-inj/
  artifacts/
    build-info/
      ...
    contracts/
      Counter.sol/
        Counter.json → open this file
        ...
  cache/
    ...
Open the Counter.json file (artifacts/contracts/Counter.sol/Counter.json). In it, you should see the compiler outputs, including the abi and bytecode fields. These artifacts are used in all later steps (test, deploy, verify, and interact).

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Next steps

Now that you have set up a Hardhat project and compiled a smart contract, you are ready to test that smart contract! Check out the test a smart contract using Hardhat tutorial next.