Building Your First Base dApp with Smart Wallets in 2026

1. What You’ll Achieve

In this guide you’ll go from an empty folder to a live Base dApp using ERC‑4337 smart wallets: you’ll deploy a simple contract to Base, wire up a Next.js frontend, and let users interact through a gas-abstracted smart wallet instead of a fragile EOA-only flow.

2. Why This Matters

Base is no longer a niche L2. As of early 2026 it secures roughly $2.1B in TVL, processes about 450,000 unique active addresses per day, and sees around $18.5B in monthly DEX volume. On top of that, roughly 1.2 million new ERC‑4337 smart wallets are being deployed on Base each month. That combination-liquidity, users, and account abstraction-makes it one of the most attractive chains to launch a new dApp.

Smart wallets (account abstraction via ERC‑4337) are what make Base feel “consumer-ready” instead of “crypto-expert-only”:

• Gas sponsorship – users can sign an action while a Paymaster pays gas in the background.
• Seedless onboarding – social logins or passkeys instead of raw seed phrases.
• Batched operations – multiple contract calls in a single “intent” (UserOperation).
• Recovery – social recovery or multi-device recovery rather than “lose seed = lose funds”.

Compared to other L2s like Arbitrum, Optimism, and zkSync, Base leans hard into this smart wallet UX and its Coinbase distribution funnel. If you care about real users instead of testnet vanity metrics, learning to ship ERC‑4337-enabled dApps on Base is a high‑leverage skill.

3. Prerequisites

This guide assumes you’re comfortable with basic Solidity, JavaScript/TypeScript, and React. You do not need prior Base or ERC‑4337 experience-we’ll layer that in as we go.

Tools you’ll need:

• Node.js 18+ and npm or pnpm installed
• Git and a code editor (VS Code works well)
• A browser wallet (MetaMask or Coinbase Wallet)
• Basic familiarity with terminal commands

Network setup – Base mainnet (for later deployment):

• Network Name: Base
• RPC URL: https://mainnet.base.org
• Chain ID: 8453
• Currency Symbol: ETH
• Block Explorer: https://basescan.org

Network setup – Base Sepolia testnet (where we’ll build first):

• Testnet Name: Base Sepolia
• RPC URL: as listed in the official Base docs (commonly https://sepolia.base.org)
• Chain ID: Base Sepolia testnet chain ID from the official docs (verify before use; values can change)
• Currency Symbol: ETH

Grab a small amount of test ETH for Base Sepolia from the faucet linked in the Base docs. For mainnet, plan to bridge or deposit at least 0.02–0.05 ETH to Base for early testing; typical interactions will cost far less, but it’s good to have a buffer.

Account abstraction concepts (very high level):

• Smart account: a contract-based account that replaces the classic EOA for the user.
• UserOperation: a structured “intent” (what the user wants to do) submitted to the network.
• EntryPoint: the core ERC‑4337 contract that validates and executes UserOperations. Canonical address (widely used across networks, including Base): 0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789.
• Bundler: a service that takes many UserOperations, bundles them, and submits one transaction.
• Paymaster: a contract that sponsors or customizes gas payments.

You’ll use a managed AA provider (like Thirdweb, Biconomy, or Stackup) so you don’t have to run your own bundler or Paymaster on day one, but you should still understand how these pieces fit.

4. Step‑by‑Step: From Empty Folder to Live Base dApp

Step 1 – Configure Base networks and funding

First, add Base mainnet and Base Sepolia to your wallet using the network values above. This lets you quickly switch between testnet and mainnet during development.

For mainnet ETH on Base later, use the official bridge:

• Go to https://bridge.base.org.
• Select Ethereum as source and Base as destination.
• Bridge a small amount (for example, 0.02–0.05 ETH) for testing.
• Deposits usually finalize on Base within a few minutes.

Once this is set, you’re ready to build almost entirely on testnet and only touch mainnet when everything is stable.

Step 2 – Scaffold your contracts with Hardhat

We’ll create a simple Counter contract that any wallet (including a smart wallet) can call to increment a number. It’s intentionally minimal so you can focus on the Base + smart wallet plumbing.

• Create a new project folder and initialize Hardhat:
  • mkdir base-aa-dapp && cd base-aa-dapp
  • npm init -y
  • npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox dotenv
  • npx hardhat → choose “Create a JavaScript project” and accept defaults.
• Create contracts/Counter.sol with the following content (single simple state change function):
  • // SPDX-License-Identifier: MIT<br>pragma solidity ^0.8.20;<br><br>contract Counter {<br>    uint256 public count;<br>    function increment() external {<br>        count += 1;<br>    }<br>}
• Compile your contracts:
  • npx hardhat compile

If compilation succeeds, your Solidity setup is sound. Once you get past this step, the rest of the contract side is straightforward.

Step 3 – Deploy the contract to Base Sepolia

This part is tricky, but stick with me—it’s critical for security. You’ll configure Hardhat to talk to Base Sepolia and keep your private key out of source control.

• Create a .env file in the project root with:
  • PRIVATE_KEY=0xYOUR_PRIVATE_KEY_WITHOUT_QUOTES
  Make sure this key controls a wallet with Base Sepolia test ETH and never commit this file.
• Update hardhat.config.js (or hardhat.config.cjs) to add a Base Sepolia network:
  • require('dotenv').config();<br>const { PRIVATE_KEY } = process.env;<br><br>module.exports = {<br>  solidity: '0.8.20',<br>  networks: {<br>    baseSepolia: {<br>      url: 'https://sepolia.base.org', // verify in Base docs<br>      chainId: YOUR_BASE_SEPOLIA_CHAIN_ID,<br>      accounts: PRIVATE_KEY ? [PRIVATE_KEY] : [],<br>    },<br>  },<br>};
• Create scripts/deploy.js:
  • async function main() {<br>  const Counter = await ethers.getContractFactory('Counter');<br>  const counter = await Counter.deploy();<br>  await counter.deployed();<br>  console.log('Counter deployed to:', counter.address);<br>}<br><br>main().catch((error) => {<br>  console.error(error);<br>  process.exitCode = 1;<br>});
• Deploy to Base Sepolia:
  • npx hardhat run scripts/deploy.js --network baseSepolia

Copy the contract address printed in the console and paste it into BaseScan (switch to Base’s Sepolia view) to confirm deployment. The deployment will typically cost far less than 0.001 ETH on testnet.

Step 4 – Wire in an ERC‑4337 smart wallet provider

This next step is where most users fail—here’s how to avoid it. The most common pitfalls are misconfigured EntryPoint addresses, missing bundler URLs, and Paymaster funding issues. Using a managed provider removes a lot of footguns.

In 2026, popular managed AA providers on Base include Thirdweb, Biconomy, and Stackup. We’ll use Thirdweb as a concrete example because it:

• Supports Base and Base Sepolia out of the box.
• Runs the ERC‑4337 bundler infrastructure for you.
• Provides audited smart account implementations and Paymaster services.

Conceptually, Thirdweb will:

• Let the user authenticate (via wallet, social login, etc.).
• Create or connect a smart account behind the scenes.
• Package the user’s “increment counter” intent into a UserOperation.
• Send it to a bundler, which calls the EntryPoint at 0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789 on Base.
• Optionally have a Paymaster sponsor gas, so users don’t see raw gas prompts.

As a dApp developer, your job is to integrate their SDK correctly and understand enough about what’s happening that you can debug when something breaks.

Step 5 – Build the Next.js + smart wallet frontend

Now you’ll create a minimal Next.js app that connects a smart wallet and calls your Counter contract on Base Sepolia.

• Scaffold the app:
  • cd .. (go one level above your Hardhat folder)
  • npx create-next-app@latest base-aa-frontend --typescript
  • cd base-aa-frontend
• Install Thirdweb React SDK and its peer dependencies:
  • npm install @thirdweb-dev/react @thirdweb-dev/sdk ethers
• Wrap your app with ThirdwebProvider in pages/_app.tsx:
  • Import the provider and Base Sepolia chain definition from Thirdweb.
  • Set activeChain to Base Sepolia and pass your Thirdweb clientId from their dashboard.
  • Example (simplified):
    • import { ThirdwebProvider } from '@thirdweb-dev/react';<br>import type { AppProps } from 'next/app';<br><br>function MyApp({ Component, pageProps }: AppProps) {<br>  return (<br>    <ThirdwebProvider activeChain="base-sepolia" clientId="YOUR_CLIENT_ID"><br>      <Component {...pageProps} /><br>    </ThirdwebProvider><br>  );<br>}<br>export default MyApp;
• In pages/index.tsx, create a simple interface:
  • A “Connect” button that initializes a smart wallet session.
  • A display of the current count from your contract.
  • A button to call increment() via the smart wallet.
  • Use Thirdweb hooks (for example, useContract, useContractRead, useContractWrite) with your Base Sepolia contract address.

At this point, you have the skeleton of a Base smart wallet dApp: a contract on Base Sepolia and a frontend that talks to it through an ERC‑4337 provider.

Step 6 – Test the full smart wallet flow on Base Sepolia

Time to test everything end‑to‑end. This is where most integration bugs surface; catching them on testnet saves you money and reputation.

• Run your frontend locally:
  • npm run dev
  • Open http://localhost:3000 in your browser.
• Connect a smart wallet:
  • Click your app’s connect button.
  • Follow the Thirdweb (or chosen provider) flow: it may ask you to sign a message or confirm smart account creation.
  • Behind the scenes, a smart account contract will be deployed on Base Sepolia when you send your first transaction.
• Read and write:
  • Load the current count via useContractRead. It should start at 0.
  • Click “Increment”. Your provider will package a UserOperation and send it to the bundler.
  • Within a few seconds, your frontend should show the updated count (for example, 1).
  • Open BaseScan in Sepolia mode, search for your smart account address or contract address, and confirm the transaction.

On Base mainnet, a transaction like this typically costs pennies or less (Base gas averages around 10 gwei, roughly 90% cheaper than Ethereum L1). If your provider sponsors gas via a Paymaster, the user might not see a gas fee at all.

Step 7 – Ship to Base mainnet

If everything works on Base Sepolia, you’re ready to ship to Base mainnet. If we could do this, so can you—this is the same pipeline most production dApps follow, just with more tests and audits.

• Add a Base mainnet network config to Hardhat:
  • networks: {<br>  base: {<br>    url: 'https://mainnet.base.org',<br>    chainId: 8453,<br>    accounts: PRIVATE_KEY ? [PRIVATE_KEY] : [],<br>  },<br>}
• Fund the deploying wallet with a small amount of ETH on Base mainnet (if you haven’t already) using https://bridge.base.org or a centralized exchange withdrawal directly to Base.
• Deploy your contract:
  • npx hardhat run scripts/deploy.js --network base
  • Record the new mainnet contract address.
• Update your frontend:
  • Switch activeChain in ThirdwebProvider from "base-sepolia" to "base".
  • Replace the testnet contract address with your mainnet contract address.
• Deploy your Next.js app to a host like Vercel or Netlify:
  • Set environment variables (client ID, contract address, etc.) in the hosting dashboard.

Once deployed, your users are interacting with Base mainnet, benefiting from its growing liquidity and user base, while enjoying the smooth UX of ERC‑4337 smart wallets.

5. Common Issues (and How to Fix Them)

Transaction stuck?

• Check the transaction or UserOperation on BaseScan (regular txs) or in your AA provider’s dashboard (UserOps).
• If gas spikes (like during the January 2026 yield events), your max fee might be too low. Resend with a slightly higher gas price if your wallet supports speeding up.
• Remember that L2 finality to Ethereum can take 1–2 minutes, but L2 inclusion itself should usually be under ~10 seconds.

Smart wallet not deploying?

• Most smart accounts deploy lazily on the first transaction. Make sure you’re actually sending a state‑changing call, not just a read.
• If you see errors like AA21 didn't pay prefund or similar, your Paymaster configuration or funding is off. Top up the Paymaster (if self‑hosted) or check your provider’s quota and configuration.
• Verify that your provider is configured for the correct chain (base-sepolia vs base) and that the EntryPoint address matches 0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789.

Bridge taking forever?

• Deposits from Ethereum to Base via bridge.base.org usually finalize within minutes. If it’s been hours, double‑check:
  • You bridged to the right address and chain.
  • The transaction is confirmed on Ethereum (check Etherscan) and on Base (check BaseScan).
• Withdrawals from Base back to Ethereum through the official bridge use optimistic proofs and can take around 7 days. For faster, more complex routes, third‑party bridges exist but add additional trust and liquidity risks.

“Insufficient liquidity” or weird prices?

• If your dApp trades tokens or relies on a DEX, Base sometimes has lower liquidity on long‑tail assets than Ethereum. Integrate with top Base DEXes (like Aerodrome or Uniswap v3 on Base) and check slippage before sending big trades.
• For testing, stick to blue‑chip assets (ETH, USDC) which have deep liquidity on Base.

6. Pro Tips: Gas, UX, and Security

Gas optimization on Base

• Batch actions with ERC‑4337: instead of multiple separate calls, have your smart account execute a single multi‑call UserOperation (for example, approve + swap + stake in one go).
• Keep storage writes minimal; even though Base is cheap, gas still adds up at scale.
• Use a gas reporter plugin in Hardhat to see which functions are expensive and refactor early.
• Transact in off‑peak hours (for example, weekends or non‑US business hours) to avoid rare congestion spikes.

UX improvements with smart wallets

• Offer gasless actions for first‑time users using a Paymaster. This dramatically improves conversion from “curious visitor” to “active on‑chain user”.
• Leverage features like session keys or spending limits (where your provider supports them) so users don’t have to approve every tiny action.
• Always support a fallback EOA flow for power users who prefer classic wallets; just treat smart wallets as the default, not the only path.

Security checklist before mainnet

• Never hardcode private keys; always use environment variables and keep .env out of version control.
• Use well‑audited smart account implementations (from providers like Thirdweb, Biconomy, or Safe‑style wallets) instead of inventing your own from scratch.
• Add unit tests and property‑based/fuzz tests for contract logic; simulate attacks like re‑entrancy and unexpected input ranges.
• Verify your contracts on BaseScan so others can inspect the source.
• For serious TVL or user volume, budget for an audit from firms like OpenZeppelin, QuillAudits, or PeckShield. Base’s core stack is audited, but your dApp logic is your responsibility.
• Monitor on‑chain metrics (via Dune, DeFiLlama, or your own dashboards) for abnormal behavior once live.

This part of the process may feel slow, but it’s where you avoid catastrophic bugs. Once you get past this step, iterating on features becomes much safer.

7. What’s Next

You’ve just built the core of a modern Base dApp: contracts deployed on Base, a smart wallet‑enabled frontend, and a grasp of ERC‑4337 fundamentals. You’re now playing in the same sandbox as apps that serve hundreds of thousands of users and tap into billions in on‑chain liquidity.

Natural next steps:

• Add richer logic: extend your contract into something useful (vault, on‑chain game, social app) while keeping gas efficiency in mind.
• Control your own Paymaster: move from fully managed sponsorship to a custom Paymaster that enforces your own rules (allowlisted methods, per‑user limits, or campaign budgets).
• Integrate with Base DeFi: plug into protocols like Aerodrome or Uniswap on Base so your users can swap, lend, or stake directly from their smart wallets.
• Instrument analytics: use Dune or a custom indexer to track UserOperations, retention, and conversion. Remember: Base currently onboards hundreds of thousands of active addresses—good analytics help you stand out.
• Prepare for audits and scale: as your user counts grow, treat security and monitoring as product features, not afterthoughts.

Base’s combination of low fees, strong developer activity, and rapidly growing smart wallet adoption means that what you built today is not a toy—it’s a blueprint. Refine it, secure it, and you’ll be ready to ship production‑grade on‑chain experiences to the next wave of users coming on Base.