Lead Blockchain Developer — ArbMarket (Prediction Market Protocol on Arbitrum)

ArbMarket is building a decentralized, non-custodial prediction market protocol on Arbitrum — think Polymarket, but Arbitrum-native from day one, with plans for ARB-denominated markets and Arbitrum ecosystem grant/incentive integration. We've already shipped an MVP: a working React frontend backed by a Node.js/Express API that mimics the on-chain flow (market creation, AMM-style pricing, orders, positions, comments). The next phase is the real one — smart contracts on Arbitrum, an indexer replacing the mock backend, wallet-native trading, and an optimistic-oracle resolution system. That's what this role owns. Why we're hiring: Our previous lead developer had to step away for health reasons. The MVP and architecture are solid and well-documented — you're not starting from zero, you're taking over a scoped, working foundation. What you'll own: Smart contract architecture (market factory, outcome-token minting/redemption, AMM pools, fee distribution, resolution module) on Arbitrum Migrating the frontend from the mock REST backend to a real indexer + direct contract calls (wagmi/RainbowKit wallet integration) Optimistic-oracle resolution design (propose → dispute window → finalize, UMA-style) Technical leadership as we scale the eng team post-conversion What we're looking for: Strong Solidity / EVM smart contract development experience (production-shipped, not just tutorials) Hands-on dApp development experience — frontend-to-contract integration, wallet connection flows, subgraph or custom indexers Comfortable in React.js and Node.js/Express (you'll need to read and extend our existing MVP codebase) Bonus: AMM or prediction-market-specific experience, familiarity with optimistic oracle patterns (UMA or similar), Arbitrum-specific deployment experience Arrangement: Fully remote. Starts as a trial contract, converting to full-time.