{"id":302,"date":"2026-10-16T07:05:38","date_gmt":"2026-10-16T07:05:38","guid":{"rendered":"https:\/\/www.comfygen.com\/blog\/?p=302"},"modified":"2026-10-16T09:44:18","modified_gmt":"2026-10-16T09:44:18","slug":"how-to-build-and-ethereum-smart-contract-in-easy-steps","status":"publish","type":"post","link":"https:\/\/www.comfygen.com\/blog\/how-to-build-and-ethereum-smart-contract-in-easy-steps\/","title":{"rendered":"How to Build an Ethereum Smart Contract in 7 Steps"},"content":{"rendered":"\r\n\r\n\r\n<p class=\"wp-block-paragraph\"><span style=\"font-weight: 400;\">Building an Ethereum smart contract takes seven steps: set up Hardhat, write the contract in Solidity, compile it, test it locally, get free testnet ETH, deploy to Sepolia, then verify it and connect your app. A simple contract goes from empty folder to live on a testnet in an afternoon.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">The tooling has changed a lot, though, and most guides still online have not caught up. Truffle and Ganache were sunset in 2023. web3.js is deprecated. The Ropsten, Rinkeby, Goerli and Holesky testnets are all shut down, so any tutorial pointing at them hands you code that fails on the first run.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">This guide uses what actually works in 2026, with full code at every step. It covers the gas you\u2019ll pay, what a contract costs to build properly, and the mistakes that lose people money after launch.<br \/><\/span><\/p>\r\n<p><strong>Key takeaways<\/strong><\/p>\r\n<ul>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">A basic Ethereum smart contract takes a few hours to write and deploy if you already know Solidity. A production contract takes four to eight weeks once testing and an audit are included.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">The current tools are Hardhat or Foundry for building, Solidity for the code, and ethers.js or viem for connecting your app. Truffle, Ganache and web3.js are no longer maintained.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Deploy to Sepolia first. It\u2019s the testnet Ethereum client teams maintain for contract and app testing, and the ETH on it is free.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Never write your own token from scratch. Use OpenZeppelin\u2019s audited contracts and extend them.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Deploying to mainnet costs gas, not a fee to anyone. The amount depends on contract size and the gas price at the moment you deploy.<br \/><\/span><\/li>\r\n<\/ul>\r\n<h3>What an Ethereum smart contract actually is<\/h3>\r\n<p><span style=\"font-weight: 400;\">A smart contract is a program that lives on the Ethereum blockchain. Once you deploy it, it runs exactly as written and nobody can change it, including you. That\u2019s the point. It also means a bug you ship is permanent.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">You write the contract in Solidity, compile it to bytecode, and send that bytecode to the network in a transaction. The contract gets its own address. After that, anyone can call its functions by sending transactions to that address.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Building one properly is a different job from building a website, and most teams bring in a<\/span><strong><span style=\"color: #5556d1;\"><a style=\"color: #5556d1;\" href=\"https:\/\/www.comfygen.com\/smart-contract-development\"> smart contract development<\/a><\/span><\/strong><span style=\"font-weight: 400;\"> partner for anything that will hold real money.<\/span><\/p>\r\n<h3>Before you start<\/h3>\r\n<p><span style=\"font-weight: 400;\">You need four things:<\/span><\/p>\r\n<ul>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Node.js installed, version 18 or later<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">A code editor, VS Code is the common choice<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">A MetaMask wallet, or any wallet that can connect to a testnet<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Some test ETH, which is free and covered in Step 5<\/span><\/li>\r\n<\/ul>\r\n<p><span style=\"font-weight: 400;\">That\u2019s it. You don\u2019t need to run your own Ethereum node, and you don\u2019t need to spend anything until you deploy to mainnet.<\/span><\/p>\r\n<h3>Step 1: Set up your development environment<\/h3>\r\n<p><span style=\"font-weight: 400;\">Start with Hardhat. It compiles your code, runs a local blockchain for testing, and handles deployment. Foundry is the other good option if you prefer writing tests in Solidity instead of JavaScript.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">bash<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">mkdir<\/span> <span style=\"font-weight: 400;\">my-contract<\/span> <span style=\"font-weight: 400;\">&amp;&amp;<\/span> <span style=\"font-weight: 400;\">cd<\/span> <span style=\"font-weight: 400;\">my-contract<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npm<\/span> <span style=\"font-weight: 400;\">init<\/span> <span style=\"font-weight: 400;\">-y<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npm<\/span> <span style=\"font-weight: 400;\">install<\/span> <span style=\"font-weight: 400;\">&#8211;save-dev<\/span> <span style=\"font-weight: 400;\">hardhat<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npx<\/span> <span style=\"font-weight: 400;\">hardhat<\/span> <span style=\"font-weight: 400;\">init<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Pick the JavaScript or TypeScript project when it asks. Hardhat creates a folder structure with <\/span><span style=\"font-weight: 400;\">contracts\/<\/span><span style=\"font-weight: 400;\">, <\/span><span style=\"font-weight: 400;\">test\/<\/span><span style=\"font-weight: 400;\"> and a config file.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">One thing worth knowing: Truffle and Ganache show up in most older tutorials, including ones published this year. Consensys sunset both in September 2023 and archived the code in early 2024. The same goes for web3.js, which is deprecated in favour of ethers.js. If a guide tells you to run <\/span><span style=\"font-weight: 400;\">truffle init<\/span><span style=\"font-weight: 400;\">, it was written for a version of Ethereum that no longer exists.<\/span><\/p>\r\n<h3>Step 2: Write the contract<\/h3>\r\n<p><span style=\"font-weight: 400;\">Create <\/span><span style=\"font-weight: 400;\">contracts\/SimpleStorage.sol<\/span><span style=\"font-weight: 400;\">. This one stores a number and lets anyone read it back:<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">solidity<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\/\/ SPDX-License-Identifier: MIT<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">pragma<\/span> <span style=\"font-weight: 400;\">solidity<\/span><span style=\"font-weight: 400;\"> ^0.8.24<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">contract<\/span><span style=\"font-weight: 400;\"> SimpleStorage<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">uint256<\/span> <span style=\"font-weight: 400;\">private<\/span><span style=\"font-weight: 400;\"> value<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">event<\/span> <span style=\"font-weight: 400;\">ValueChanged<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">uint256<\/span> <span style=\"font-weight: 400;\">newValue<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">function<\/span> <span style=\"font-weight: 400;\">set<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">uint256<\/span> <span style=\"font-weight: 400;\">newValue<\/span><span style=\"font-weight: 400;\">)<\/span> <span style=\"font-weight: 400;\">public<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0value = newValue<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">emit<\/span> <span style=\"font-weight: 400;\">ValueChanged<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">newValue<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">function<\/span> <span style=\"font-weight: 400;\">get<\/span><span style=\"font-weight: 400;\">()<\/span> <span style=\"font-weight: 400;\">public<\/span> <span style=\"font-weight: 400;\">view<\/span> <span style=\"font-weight: 400;\">returns<\/span> <span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">uint256<\/span><span style=\"font-weight: 400;\">)<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">return<\/span><span style=\"font-weight: 400;\"> value<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">A few things to notice. The <\/span><span style=\"font-weight: 400;\">event<\/span><span style=\"font-weight: 400;\"> is how your contract tells the outside world something happened, since your app can\u2019t watch storage directly. The <\/span><span style=\"font-weight: 400;\">view<\/span><span style=\"font-weight: 400;\"> keyword on <\/span><span style=\"font-weight: 400;\">get()<\/span><span style=\"font-weight: 400;\"> means it reads data without changing anything, so calling it is free. And the pragma line pins the compiler version, which you should set to the current 0.8.x release rather than leaving it loose.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">If you\u2019re building a token rather than a storage contract, skip writing it yourself. Import OpenZeppelin instead:<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">bash<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npm<\/span> <span style=\"font-weight: 400;\">install<\/span> <span style=\"font-weight: 400;\">@openzeppelin\/contracts<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">solidity<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\/\/ SPDX-License-Identifier: MIT<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">pragma<\/span> <span style=\"font-weight: 400;\">solidity<\/span><span style=\"font-weight: 400;\"> ^0.8.24<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">import<\/span> <span style=\"font-weight: 400;\">&#8220;@openzeppelin\/contracts\/token\/ERC20\/ERC20.sol&#8221;<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">contract<\/span> <span style=\"font-weight: 400;\">MyToken<\/span> <span style=\"font-weight: 400;\">is<\/span> <span style=\"font-weight: 400;\">ERC20<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">constructor<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">uint256<\/span> <span style=\"font-weight: 400;\">initialSupply<\/span><span style=\"font-weight: 400;\">) <\/span><span style=\"font-weight: 400;\">ERC20<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;MyToken&#8221;, &#8220;MTK&#8221;) <\/span><span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">_mint<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">msg.sender<\/span><span style=\"font-weight: 400;\">,<\/span><span style=\"font-weight: 400;\"> initialSupply * <\/span><span style=\"font-weight: 400;\">10<\/span><span style=\"font-weight: 400;\"> ** <\/span><span style=\"font-weight: 400;\">decimals<\/span><span style=\"font-weight: 400;\">());<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">That\u2019s a complete, standards-compliant token in nine lines. Hand-written token contracts almost always get something wrong, usually the transfer events, and then wallets and explorers display the balances incorrectly. Teams launching their own<\/span><strong><span style=\"color: #5556d1;\"><a style=\"color: #5556d1;\" href=\"https:\/\/www.comfygen.com\/erc20-token-development\"> ERC-20 token<\/a><\/span><\/strong><span style=\"font-weight: 400;\"> start from this base and add features on top.<\/span><\/p>\r\n<h3>Step 3: Compile<\/h3>\r\n<p><span style=\"font-weight: 400;\">bash<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npx<\/span> <span style=\"font-weight: 400;\">hardhat<\/span> <span style=\"font-weight: 400;\">compile<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Hardhat downloads the right Solidity compiler and produces the ABI and bytecode in an <\/span><span style=\"font-weight: 400;\">artifacts\/<\/span><span style=\"font-weight: 400;\"> folder. The ABI is the list of functions your contract exposes, and your frontend needs it later.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Fix every warning, not just the errors. Solidity warnings usually point at something that will cost you gas or behave unexpectedly.<\/span><\/p>\r\n<h3>Step 4: Test locally<\/h3>\r\n<p><span style=\"font-weight: 400;\">This is the step people skip, and it\u2019s the one that saves money. Hardhat gives you a local blockchain that resets between tests, so you can run a thousand scenarios in seconds at no cost.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Create <\/span><span style=\"font-weight: 400;\">test\/SimpleStorage.js<\/span><span style=\"font-weight: 400;\">:<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">javascript<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">const<\/span> <span style=\"font-weight: 400;\">{<\/span><span style=\"font-weight: 400;\"> expect <\/span><span style=\"font-weight: 400;\">}<\/span><span style=\"font-weight: 400;\"> = <\/span><span style=\"font-weight: 400;\">require<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;chai&#8221;<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">describe<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;SimpleStorage&#8221;<\/span><span style=\"font-weight: 400;\">,<\/span> <span style=\"font-weight: 400;\">function<\/span> <span style=\"font-weight: 400;\">()<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">it<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;stores and returns a value&#8221;<\/span><span style=\"font-weight: 400;\">,<\/span> <span style=\"font-weight: 400;\">async<\/span> <span style=\"font-weight: 400;\">function<\/span> <span style=\"font-weight: 400;\">()<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> Storage = <\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> ethers<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">getContractFactory<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;SimpleStorage&#8221;<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> storage = <\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> Storage<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">deploy<\/span><span style=\"font-weight: 400;\">();<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> storage<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">set<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">42<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">expect<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> storage<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">get<\/span><span style=\"font-weight: 400;\">()).<\/span><span style=\"font-weight: 400;\">to<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">equal<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">42<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">});<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">});<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">bash<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npx<\/span> <span style=\"font-weight: 400;\">hardhat<\/span> <span style=\"font-weight: 400;\">test<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Test the failure cases too, not just the happy path. What happens when someone calls a function they shouldn\u2019t have access to? What happens with a zero value, or a number large enough to overflow? Those are where the money goes missing.<\/span><\/p>\r\n<h3>Step 5: Get testnet ETH<\/h3>\r\n<p><span style=\"font-weight: 400;\">Sepolia is the testnet to use. Ethereum\u2019s client teams currently maintain two public testnets, Sepolia for contract and application testing, and Hoodi for validator and staking testing. Older guides point at Ropsten, Rinkeby, Goerli or Holesky. All four are shut down, so their faucets and RPC endpoints return errors.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Get free Sepolia ETH from a faucet run by Alchemy, QuickNode or Google Cloud. You\u2019ll need to paste your wallet address and wait a minute or two.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">One caution worth building into your process: testnets get retired on a schedule now. Sepolia has an estimated end of life around the end of September 2026. Check the networks page on ethereum.org before you start a new project rather than copying a network name out of a tutorial.<\/span><\/p>\r\n<h3>Step 6: Deploy to the testnet<\/h3>\r\n<p><span style=\"font-weight: 400;\">Add your network to <\/span><span style=\"font-weight: 400;\">hardhat.config.js<\/span><span style=\"font-weight: 400;\">. Keep the private key in an environment variable, never in the file itself:<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">javascript<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">require<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;@nomicfoundation\/hardhat-toolbox&#8221;<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">module<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">exports<\/span><span style=\"font-weight: 400;\"> = <\/span><span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">solidity<\/span><span style=\"font-weight: 400;\">:<\/span> <span style=\"font-weight: 400;\">&#8220;0.8.24&#8221;<\/span><span style=\"font-weight: 400;\">,<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">networks<\/span><span style=\"font-weight: 400;\">:<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">sepolia<\/span><span style=\"font-weight: 400;\">:<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">url<\/span><span style=\"font-weight: 400;\">:<\/span><span style=\"font-weight: 400;\"> process<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">env<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">SEPOLIA_RPC_URL<\/span><span style=\"font-weight: 400;\">,<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">accounts<\/span><span style=\"font-weight: 400;\">:<\/span> <span style=\"font-weight: 400;\">[<\/span><span style=\"font-weight: 400;\">process<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">env<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">PRIVATE_KEY<\/span><span style=\"font-weight: 400;\">]<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">};<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Write a deploy script in <\/span><span style=\"font-weight: 400;\">scripts\/deploy.js<\/span><span style=\"font-weight: 400;\">:<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">javascript<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">async<\/span> <span style=\"font-weight: 400;\">function<\/span> <span style=\"font-weight: 400;\">main<\/span><span style=\"font-weight: 400;\">()<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> Storage = <\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> ethers<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">getContractFactory<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;SimpleStorage&#8221;<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> storage = <\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> Storage<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">deploy<\/span><span style=\"font-weight: 400;\">();<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0<\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> storage<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">waitForDeployment<\/span><span style=\"font-weight: 400;\">();<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0console<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">log<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">&#8220;Deployed to:&#8221;<\/span><span style=\"font-weight: 400;\">,<\/span> <span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> storage<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">getAddress<\/span><span style=\"font-weight: 400;\">());<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">}<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">main<\/span><span style=\"font-weight: 400;\">().<\/span><span style=\"font-weight: 400;\">catch<\/span><span style=\"font-weight: 400;\">((<\/span><span style=\"font-weight: 400;\">error<\/span><span style=\"font-weight: 400;\">)<\/span> <span style=\"font-weight: 400;\">=&gt;<\/span> <span style=\"font-weight: 400;\">{<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0console<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">error<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">error<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0\u00a0process<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">exitCode = <\/span><span style=\"font-weight: 400;\">1<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">});<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">bash<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npx<\/span> <span style=\"font-weight: 400;\">hardhat<\/span> <span style=\"font-weight: 400;\">run<\/span> <span style=\"font-weight: 400;\">scripts\/deploy.js<\/span> <span style=\"font-weight: 400;\">&#8211;network<\/span> <span style=\"font-weight: 400;\">sepolia<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">You\u2019ll get a contract address back. Paste it into sepolia.etherscan.io and you can see your contract on the network.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">A private key in a committed <\/span><span style=\"font-weight: 400;\">.env<\/span><span style=\"font-weight: 400;\"> file is the most common way beginners lose funds. Add <\/span><span style=\"font-weight: 400;\">.env<\/span><span style=\"font-weight: 400;\"> to <\/span><span style=\"font-weight: 400;\">.gitignore<\/span><span style=\"font-weight: 400;\"> before you write anything into it.<\/span><\/p>\r\n<h3>Step 7: Verify and connect your app<\/h3>\r\n<p><span style=\"font-weight: 400;\">Verifying publishes your source code on Etherscan so people can read what the contract actually does. Most users won\u2019t touch an unverified contract, and for good reason.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">bash<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">npx<\/span> <span style=\"font-weight: 400;\">hardhat<\/span> <span style=\"font-weight: 400;\">verify<\/span> <span style=\"font-weight: 400;\">&#8211;network<\/span> <span style=\"font-weight: 400;\">sepolia<\/span> <span style=\"font-weight: 400;\">YOUR_CONTRACT_ADDRESS<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">To call the contract from a web app, use ethers.js with the ABI from Step 3:<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">javascript<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">import<\/span> <span style=\"font-weight: 400;\">{<\/span><span style=\"font-weight: 400;\"> ethers <\/span><span style=\"font-weight: 400;\">}<\/span> <span style=\"font-weight: 400;\">from<\/span> <span style=\"font-weight: 400;\">&#8220;ethers&#8221;<\/span><span style=\"font-weight: 400;\">;<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> provider = <\/span><span style=\"font-weight: 400;\">new<\/span><span style=\"font-weight: 400;\"> ethers<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">BrowserProvider<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">window<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">ethereum<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> signer = <\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> provider<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">getSigner<\/span><span style=\"font-weight: 400;\">();<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> contract = <\/span><span style=\"font-weight: 400;\">new<\/span><span style=\"font-weight: 400;\"> ethers<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">Contract<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">address<\/span><span style=\"font-weight: 400;\">,<\/span><span style=\"font-weight: 400;\"> abi<\/span><span style=\"font-weight: 400;\">,<\/span><span style=\"font-weight: 400;\"> signer<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">\u00a0<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> contract<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">set<\/span><span style=\"font-weight: 400;\">(<\/span><span style=\"font-weight: 400;\">100<\/span><span style=\"font-weight: 400;\">);<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">const<\/span><span style=\"font-weight: 400;\"> result = <\/span><span style=\"font-weight: 400;\">await<\/span><span style=\"font-weight: 400;\"> contract<\/span><span style=\"font-weight: 400;\">.<\/span><span style=\"font-weight: 400;\">get<\/span><span style=\"font-weight: 400;\">();<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">That\u2019s the full loop. Everything after this is the same code deployed against mainnet instead of Sepolia, which is why building the<\/span><strong><span style=\"color: #5556d1;\"><a style=\"color: #5556d1;\" href=\"https:\/\/www.comfygen.com\/dapp-development-company\"> dApp<\/a><\/span><\/strong><span style=\"font-weight: 400;\"> around a tested contract is the easier half of the work.<br \/><\/span><\/p>\r\n<h3>How Ethereum runs your contract<\/h3>\r\n<p><span style=\"font-weight: 400;\">Ethereum switched to proof of stake in September 2022. Validators stake ETH, get selected to propose blocks, and attest to each other\u2019s blocks. There\u2019s no mining and no puzzle solving involved, which is a detail a lot of older content still gets wrong.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">When you send a transaction to a contract, it enters the mempool. A validator picks it up and includes it in a block. Every node on the network then runs your contract code in the Ethereum Virtual Machine and arrives at the same result. That agreement is what makes the outcome trustworthy.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">You pay for the computation in gas. Each operation has a gas cost, and you pay that gas multiplied by the current gas price. Storing data is expensive, reading it is cheap, and anything you can calculate off chain should be.<br \/><\/span><\/p>\r\n<h3>What it costs<\/h3>\r\n<p><span style=\"font-weight: 400;\">Two separate costs, and people mix them up.<\/span><\/p>\r\n<p><b>Gas<\/b><span style=\"font-weight: 400;\"> is what you pay the network to deploy and run the contract. A simple contract like the one above costs somewhere between 300,000 and 800,000 gas to deploy. Multiply that by the gas price in gwei at the moment you deploy, which swings a lot. Check the Etherscan gas tracker and deploy during a quiet period if timing is flexible.<\/span><\/p>\r\n<p>Development<span style=\"font-weight: 400;\"> is what it costs to build the thing properly.<br \/><br \/><\/span><\/p>\r\n<table>\r\n<tbody>\r\n<tr>\r\n<td>\r\n<p><b>Project type<\/b><\/p>\r\n<\/td>\r\n<td>\r\n<p><b>Typical range<\/b><\/p>\r\n<\/td>\r\n<td>\r\n<p><b>Timeline<\/b><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Single simple contract<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">$3,000 to $8,000<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">1 to 2 weeks<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Standard token with vesting and admin controls<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">$8,000 to $20,000<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">3 to 5 weeks<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">DeFi protocol or multi contract system<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">$30,000 and up<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">10 weeks and up<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Third party security audit<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">$8,000 to $50,000<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">2 to 4 weeks<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p><span style=\"font-weight: 400;\">Audits aren\u2019t optional once real money is involved. The cost of an audit is always smaller than the cost of an exploit. Broader figures are covered in the<\/span><span style=\"color: #5556d1;\"><strong><a style=\"color: #5556d1;\" href=\"https:\/\/www.comfygen.com\/blog\/blockchain-development-cost\/\"> blockchain development cost<\/a><\/strong><\/span><span style=\"font-weight: 400;\"> breakdown.<\/span><\/p>\r\n<h3>Where else you can deploy<\/h3>\r\n<p><span style=\"font-weight: 400;\">Ethereum isn\u2019t the only option, and for some projects it isn\u2019t the right one.<\/span><\/p>\r\n<table>\r\n<tbody>\r\n<tr>\r\n<td>\r\n<p><b>Platform<\/b><\/p>\r\n<\/td>\r\n<td>\r\n<p><b>Language<\/b><\/p>\r\n<\/td>\r\n<td>\r\n<p><b>Best for<\/b><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Ethereum<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Solidity<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Highest security and liquidity, the default for DeFi<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Polygon<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Solidity<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Same code as Ethereum, far lower fees<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Arbitrum, Base, Optimism<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Solidity<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Ethereum security with layer 2 costs<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Solana<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Rust<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">High transaction volume, consumer apps<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<tr>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Hyperledger Fabric<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Go, Java<\/span><\/p>\r\n<\/td>\r\n<td>\r\n<p><span style=\"font-weight: 400;\">Private enterprise networks, no public chain<\/span><\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<p><span style=\"font-weight: 400;\">Because Polygon and the layer 2 networks run the same EVM, a contract written for Ethereum deploys to them with no code changes. That\u2019s usually the first thing to try if gas costs are the blocker. Projects that need thousands of transactions per second tend to look at<\/span><a href=\"https:\/\/www.comfygen.com\/solana-blockchain-development-company\"> <span style=\"font-weight: 400;\">Solana<\/span><\/a><span style=\"font-weight: 400;\"> instead, which means rewriting in Rust.<\/span><\/p>\r\n<h3>Mistakes that cost people money<\/h3>\r\n<ul>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Reentrancy.<\/b><span style=\"font-weight: 400;\"> A contract calls out to another contract, which calls back in before the first one finishes updating its state. Update state before making external calls, and use OpenZeppelin\u2019s <\/span><span style=\"font-weight: 400;\">ReentrancyGuard<\/span><span style=\"font-weight: 400;\">.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>No access control.<\/b><span style=\"font-weight: 400;\"> Any function that shouldn\u2019t be public needs an <\/span><span style=\"font-weight: 400;\">onlyOwner<\/span><span style=\"font-weight: 400;\"> modifier or a role check. Leaving a mint function open is a common and fatal error.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Hardcoded addresses.<\/b><span style=\"font-weight: 400;\"> Addresses differ between testnet and mainnet. Pass them in through the constructor.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>Unbounded loops.<\/b><span style=\"font-weight: 400;\"> A loop over an array that grows forever will eventually run out of gas and brick the function.<\/span><\/li>\r\n<li style=\"font-weight: 400;\" aria-level=\"1\"><b>No upgrade path.<\/b><span style=\"font-weight: 400;\"> Contracts are permanent. If you\u2019ll need to fix bugs later, build on a proxy pattern from day one, and understand the tradeoffs before you do.<\/span><\/li>\r\n<\/ul>\r\n<h3>Building something that holds real value<\/h3>\r\n<p><span style=\"font-weight: 400;\">Smart contracts fail in ways normal software doesn\u2019t. There\u2019s no hotfix, no rollback, and the attack surface is open to everyone on the internet with an incentive to break it.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">Comfygen has worked on blockchain and smart contract projects since 2019, across 550+ projects for 400+ clients in 30+ countries, with 97% client retention. Our team builds on Solidity, Rust and the EVM layer 2 networks, and every contract we ship goes through internal review before it reaches an external auditor.<\/span><\/p>\r\n<p><span style=\"font-weight: 400;\">If you\u2019re planning a token, a DeFi protocol or a custom contract and want a second opinion on the approach,<\/span><strong><span style=\"color: #5556d1;\"><a style=\"color: #5556d1;\" href=\"https:\/\/www.comfygen.com\/contact-us\"> talk to our team<\/a><\/span><\/strong><span style=\"font-weight: 400;\"><strong><span style=\"color: #5556d1;\">.<br \/><\/span><\/strong><br \/><\/span><\/p>\r\n<h2>FAQ\u2019s<\/h2>\r\n<style>\n\t\t#faqsu-faq-list {\n\t\t\tbackground: #F0F4F8;\n\t\t\tborder-radius: 5px;\n\t\t\tpadding: 15px;\n\t\t}\n\t\t#faqsu-faq-list .faqsu-faq-single {\n\t\t\tbackground: #fff;\n\t\t\tpadding: 15px 15px 20px;\n\t\t\tbox-shadow: 0px 0px 10px #d1d8dd, 0px 0px 40px #ffffff;\n\t\t\tborder-radius: 5px;\n\t\t\tmargin-bottom: 1rem;\n\t\t}\n\t\t#faqsu-faq-list .faqsu-faq-single:last-child {\n\t\t\tmargin-bottom: 0;\n\t\t}\n\t\t#faqsu-faq-list .faqsu-faq-question {\n\t\t\tborder-bottom: 1px solid #F0F4F8;\n\t\t\tpadding-bottom: 0.825rem;\n\t\t\tmargin-bottom: 0.825rem;\n\t\t\tposition: relative;\n\t\t\tpadding-right: 40px;\n\t\t}\n\t\t#faqsu-faq-list .faqsu-faq-question:after {\n\t\t\tcontent: \"?\";\n\t\t\tposition: absolute;\n\t\t\tright: 0;\n\t\t\ttop: 0;\n\t\t\twidth: 30px;\n\t\t\tline-height: 30px;\n\t\t\ttext-align: center;\n\t\t\tcolor: #c6d0db;\n\t\t\tbackground: #F0F4F8;\n\t\t\tborder-radius: 40px;\n\t\t\tfont-size: 20px;\n\t\t}\n\t\t<\/style>\n\t\t\n\t\t<section id=\"faqsu-faq-list\" itemscope itemtype=\"http:\/\/schema.org\/FAQPage\"><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">How long does it take to build an Ethereum smart contract?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">\u00a0A basic contract takes a few hours. A production contract takes four to eight weeks once you include testing, a security audit and the frontend.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">Do I need to know Solidity?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">\u00a0For custom contracts, yes. Solidity looks a lot like JavaScript, and most developers with backend experience pick up the basics in a week or two. The hard part is security, not syntax.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">Which testnet should I use in 2026?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">Sepolia for contract and application testing. Hoodi is for validator and staking testing. Ropsten, Rinkeby, Goerli and Holesky are all shut down.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">How much gas does deployment cost?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">A simple contract runs 300,000 to 800,000 gas. The dollar cost depends entirely on the gas price when you deploy, so check a gas tracker first.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">Can a smart contract be changed after deployment?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">\u00a0Not directly. You can design an upgradeable contract using a proxy pattern, where the logic sits in a second contract you can swap out. Plan this before you deploy, because you can\u2019t add it later.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">Is Truffle still usable?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">\u00a0No. Consensys sunset Truffle and Ganache in 2023 and archived the repositories. Use Hardhat or Foundry.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><div class=\"faqsu-faq-single\" itemscope itemprop=\"mainEntity\" itemtype=\"https:\/\/schema.org\/Question\">\n\t\t\t\t\t<h3 class=\"faqsu-faq-question\" itemprop=\"name\">What\u2019s the difference between a smart contract and a dApp?<\/h3>\n\t\t\t\t\t<div itemscope itemprop=\"acceptedAnswer\" itemtype=\"https:\/\/schema.org\/Answer\">\n\t\t\t\t\t\t<div class=\"faqsu-faq-answare\" itemprop=\"text\"><p><span style=\"font-weight: 400\">The smart contract is the on chain logic. The dApp is the application users interact with, which includes a web or mobile frontend that talks to the contract.<\/span><\/p><\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div><\/section>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\"><\/p>","protected":false},"excerpt":{"rendered":"<p>Building an Ethereum smart contract takes seven steps: set up Hardhat, write the contract in Solidity, compile it, test it locally, get free testnet ETH, deploy to Sepolia, then verify it and connect your app. A simple contract goes from empty folder to live on a testnet in an afternoon. The tooling has changed a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":10945,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"two_page_speed":[],"footnotes":""},"categories":[117],"tags":[58,60,59],"class_list":["post-302","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blockchain","tag-ethereum-smart-contract","tag-smart-contract","tag-smart-contract-development"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.5 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>How to Build an Ethereum Smart Contract in 7 Steps (2026)<\/title>\n<meta name=\"description\" content=\"Build and deploy an Ethereum smart contract in 7 steps. 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