Web 3 Engineer

As a Web3 Engineer at GradientFI, you own features end-to-end across a Web3 payment infrastructure platform that lets users and merchants move value across multiple blockchains. You work from on-chain integration through backend services to the user-facing product, balancing blockchain complexity with product delivery.

What you'll do

• Build and maintain integrations with multiple blockchains such as Bitcoin, Ethereum, and other EVM chains, handling transaction construction, broadcasting, and confirmation logic.
• Write, test, and deploy smart contracts in Solidity or equivalent languages for deposits, withdrawals, and on-chain logic.
• Design and build backend services and APIs including ledger logic, merchant payment endpoints, and webhooks that connect on-chain activity to the rest of the product.
• Build frontend features for the wallet, merchant dashboard, or checkout flows in React or similar, consuming the APIs and on-chain data you create.
• Own features across the full stack from a contract or chain integration through the API layer to the UI a user or merchant touches.
• Write tests covering blockchain-specific edge cases such as chain reorgs, stuck transactions, and gas estimation, alongside standard backend and frontend test coverage.
• Monitor and maintain blockchain nodes and related infrastructure as needed.
• Collaborate with product, design, and security teams on features that handle real funds.

What you bring

• Experience building on at least one major blockchain platform (Ethereum, EVM chains, Bitcoin, Solana, or equivalent), including writing and testing smart contracts if EVM-based.
• A solid understanding of blockchain fundamentals: wallets, transactions, gas and fees, confirmations, and finality.
• Full-stack development experience with both backend (Node.js, Go, Python, Rust, or similar) and frontend (React or similar), building and consuming APIs across both layers.
• Understanding of common Web3 security pitfalls including reentrancy, front-running, and key management.
• Comfort with Git, CI/CD pipelines, and standard software engineering practices.
• Ability to work independently across the stack without needing every layer handed off by a specialist.

Nice to have

• Experience with multi-chain integrations in production across more than one blockchain.
• Familiarity with wallet SDKs, RPC providers, or indexing tools such as The Graph.
• Experience with payment systems, exchanges, or custodial platforms.
• Exposure to Layer 2 solutions, cross-chain bridges, or account abstraction.
• Mobile development experience on iOS or Android if the product includes a mobile wallet.
• Contributions to open-source Web3 projects.