Fuel - Senior Web3 Software Engineer

Fuel is a high-performance blockchain operating system that redefines what's possible on Ethereum by combining unparalleled throughput with decentralization and security. As a Senior Web3 Software Engineer at deCircle, you will lead the development of high-performance decentralized applications in a blockchain-native environment. You own major product surfaces end-to-end, from frontend interfaces to on-chain integrations, collaborating closely with product, design, backend, and smart contract teams to ship secure, reliable, and intuitive experiences for traders and users.

What you'll do

• Design, build, and maintain modern, responsive frontend applications integrated with blockchain protocols for core DeFi products like exchanges.
• Integrate with blockchain infrastructure such as EVM chains and Fuel VM, wallet extensions like MetaMask, Phantom, and WalletConnect, and on-chain data sources including subgraphs and indexers.
• Implement secure user flows for transactions, multi-sig approvals, cross-chain bridging, and account abstraction.
• Collaborate on API design using REST and GraphQL, RPC optimization, and indexer queries for real-time data.
• Establish frontend architecture, design systems, and Web3 best practices including testing with Hardhat and Foundry, gas optimization, reentrancy guards, and accessibility.
• Review code including Solidity and Sway, mentor engineers, and drive technical decisions on stack interoperability and scalability.
• Translate complex DeFi requirements such as MEV protection and oracle feeds into intuitive UI and UX for trading interfaces.
• Proactively identify technical debt in smart contracts or frontend, propose upgrades such as account abstraction, and shape the product roadmap technically.

What you bring

• 5+ years of professional experience as a software engineer, with 2+ years in a senior or lead capacity building Web3 or blockchain applications.
• Deep expertise in modern frontend frameworks such as React, Next.js, and Vue with TypeScript and JavaScript, plus Web3 libraries including ethers.js, viem, and wagmi.
• Strong experience with complex, data-intensive dapps handling real-time streams such as order books and AMM curves.
• Proven blockchain integration skills: browser wallet connections and signing, on-chain interactions via providers like Alchemy and Infura, and libraries for reads, writes, and calls.
• A solid grasp of Web3 security including private key management, blind signing risks, phishing, and sandwich attacks.
• Backend experience with node services such as Express and FastAPI, off-chain indexers like The Graph, and event listening.
• Proficiency in REST and GraphQL, data fetching using SWR and TanStack Query, and state management with Zustand and Redux in volatile crypto contexts.
• Excellent collaboration in fast-paced, autonomous teams using GitHub, Linear, and Discord or Slack.

Nice to have

• Experience at a CEX or DEX such as Uniswap, Fuel's O2, or KuCoin integrations.
• Building trading UIs including order books, candlestick charts via TradingView or Lightweight Charts, positions, and PnL calculators.
• Performance tuning for high-throughput DeFi with sub-millisecond latency and WebSockets for orderflow.
• Prior DeFi or fintech work with tokenomics, liquidity mining, or audited protocols.
• Design systems such as RainbowKit and Wagmi connectors, and tooling including Vite, esbuild, and Foundry for end-to-end tests.