Senior Full-Stack Developer — E-commerce + Crypto Wallet

We’re looking for an experienced Senior Full-Stack Developer to improve an existing e-commerce application and add crypto wallet/payment functionality. This is not a greenfield project. The application is already functional, so we need someone who can understand the existing codebase and improve it without unnecessary rewrites. 🛠️ What You’ll Do 🔍 Review and modernize the existing application ⚡ Improve architecture, APIs, validation, performance, and error handling 💳 Improve the existing payment architecture 🦊 Integrate browser wallets such as MetaMask/Rabby ⛓️ Add EVM/testnet cryptocurrency payments 🔐 Implement backend blockchain transaction verification 🧾 Connect crypto payments with existing orders 🔄 Handle pending, failed, cancelled, and successful transactions 🧪 Test and stabilize the complete payment flow 💻 Tech Stack React + TypeScript Node.js + Express SQLite REST APIs Ethereum / EVM MetaMask / Rabby / WalletConnect ethers.js / viem / wagmi ⭐ We’re Looking For Strong full-stack development experience Experience working with existing applications E-commerce and payment integration experience Practical Web3/blockchain experience Strong TypeScript skills Understanding of payment and transaction security Ability to work independently and make pragmatic technical decisions Comfortable using AI coding tools while understanding the code being produced 📩 Please Include React/Node.js experience E-commerce/payment experience Web3 and crypto wallet experience Wallets/libraries you’ve worked with Similar projects you've completed Estimated timeline Hourly rate or fixed-price estimate Availability 🚫 No full rewrite proposals, please. We want someone who can modernize what already works and integrate crypto payments properly. 🌐 Initial development will use testnet only — no real cryptocurrency required.