Senior Web3 / Crypto Exchange Developer – Non-Custodial Trading Platform

We are looking for an experienced Web3 / Blockchain engineer to help build and improve a non-custodial crypto exchange platform. The ideal candidate has hands-on experience building real-world crypto products such as exchanges, wallets, DEX integrations, and blockchain payment systems. Current Platform Features: - Non-custodial crypto exchange architecture - EVM-based wallet management - Wallet connection and embedded wallet integration - Fiat-to-crypto onramp integration - Token swap functionality through DEX protocols - Deposit and withdrawal flows - Smart contract interactions - Admin-controlled escrow workflow - Transaction monitoring and security improvements Responsibilities: - Review and improve current exchange architecture - Help optimize wallet and transaction flows - Implement and improve DEX swap integrations - Integrate and troubleshoot crypto payment/onramp providers - Improve blockchain security practices - Review smart contract interactions and transaction handling - Help prepare the platform for production launch Required Experience: - Strong experience building crypto exchange or DeFi applications - Deep understanding of EVM chains (Ethereum, Polygon, Base, etc.) - Experience with DEX integrations (0x, Uniswap, 1inch, etc.) - Experience with wallet integrations (Privy, WalletConnect, Web3Auth, etc.) - Experience handling blockchain transactions securely - Understanding of non-custodial wallet architecture - Experience with crypto onramp/offramp providers (Stripe, MoonPay, Transak, etc.) Technical Skills: - Solidity / Smart Contract interaction - ethers.js / viem / web3.js - Node.js / TypeScript - React / Next.js - PostgreSQL or similar databases - REST/WebSocket blockchain APIs Security Knowledge (Important): Candidates should understand: - Private key security - Wallet architecture - Transaction signing flows - Replay attack prevention - Smart contract risks - User asset protection in non-custodial systems Nice to Have: - Experience launching crypto products to production - Experience with compliance/KYB/KYC integrations - Experience with US crypto regulations - Experience with healthcare or data marketplace Web3 projects