Fun.xyz - Protocol Engineer

At Fun.xyz , we believe a tokenized future is a beneficial inevitability, granting financial emancipation to everyone with an internet connection. For a blockchain-first global economy to exist, value exchange must become intuitive, secure, and seamless. Enter Checkout - the highest converting payment solution in web3. By integrating Checkout, dApps enable users to complete any on-chain action using crypto from a wallet, centralized exchange, or on-ramped fiat from a card or bank account. With access to market-leading routing and their asset portfolio at the point of sale, users are faster, stickier, and more engaged. We built Checkout because we envision a world where anyone, anywhere, can purchase anything with any asset. If that sounds like a vision you can get behind, we want to hear from you. Role Overview We're looking for a Protocol Engineer to join our core blockchain team and help build the foundation of Web3 payments infrastructure. This high-impact role offers the opportunity to work on challenging technical problems at the intersection of smart contracts, cross-chain protocols, and decentralized finance. You will design and implement secure, efficient smart contract systems and blockchain integrations that power millions of transactions across multiple chains. This role is perfect for a technically strong engineer who thrives in fast-paced environments and wants to shape the future of decentralized finance. Responsibilities Design, develop, and deploy secure smart contracts and protocol implementations across multiple blockchain platforms Collaborate with backend and product teams to architect blockchain solutions that meet business requirements Write highly efficient, well-tested code and participate in security audits to ensure protocol safety Research and evaluate new blockchain technologies, protocols, and DeFi primitives for integration opportunities Contribute to incident response and debugging on-chain issues to ensure protocol reliability Strong experience building and deploying production smart contracts on major blockchain platforms Deep understanding of blockchain architecture, consensus mechanisms, and cryptographic principles Hands-on experience with smart contract development languages (Solidity, Rust, Move, etc.) Solid grasp of DeFi protocols, token standards, and cross-chain communication patterns Strong security mindset with knowledge of common smart contract vulnerabilities and best practices Clear communicator who can explain complex blockchain concepts to cross-functional teams Nice to Have Production experience with multiple blockchain ecosystems (Ethereum, Solana, L2s, etc.) Previously worked at crypto startup or Web3 infrastructure company Experience with cross-chain bridges, oracles, or interoperability protocols Background with high-volume DeFi protocols or DEX infrastructure Contributions to blockchain open source projects or protocol research Experience with formal verification or advanced smart contract testing frameworks