Web3 + Full Stack Engineer

As a Web3 + Full Stack Engineer at GradientFI, you own features end-to-end for Web3 payment infrastructure that lets users and merchants move value across multiple blockchains. You'll work across on-chain integration, backend services, and user-facing products, bringing together blockchain knowledge with full-stack development skills.

What you'll do

• Build and maintain integrations with multiple blockchains (Bitcoin, Ethereum, and other EVM chains), including transaction construction, broadcasting, and confirmation handling.
• Write, test, and deploy smart contracts in Solidity or equivalent for deposits, withdrawals, and on-chain logic.
• Design and build backend services and APIs covering 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 using React or similar, consuming the APIs and on-chain data you create.
• Own complete features across the stack from contract or chain integration through the API layer to the UI users and merchants interact with.
• 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 on features that handle real funds.

What you bring

• Experience building on at least one major blockchain platform (Ethereum/EVM, Bitcoin, Solana, etc.), 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 backend technologies (Node.js, Go, Python, Rust, or similar) and frontend frameworks (React or similar), building and consuming APIs across both layers.
• Understanding of common security pitfalls in Web3 development such as reentrancy, front-running, and key management.
• Comfort working with Git, CI/CD, 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.
• Familiarity with wallet SDKs, RPC providers, or indexing tools such as The Graph.
• Experience with payment systems, exchanges, or custodial platforms.
• Exposure to Layer 2s, cross-chain bridges, or account abstraction.
• Mobile development experience for iOS or Android, if the product includes a mobile wallet.
• Contributions to open-source Web3 projects.