Protocol Engineer, Web3 Payments Infrastructure

About the role

Fun builds the infrastructure behind consumer-facing fintech applications, handling onboarding, account access and money movement so users can interact with blockchain-based systems as easily as with traditional finance. It is looking for a Protocol Engineer to join its core blockchain team and help build the foundation of Web3 payments infrastructure. You will design and implement secure, efficient smart contract systems and blockchain integrations that power millions of transactions across multiple chains.

Key responsibilities

• Design, develop and deploy secure smart contracts and protocol implementations across multiple blockchain platforms
• Work with backend and product teams to architect blockchain solutions that meet business requirements
• Write efficient, well-tested code and take part in security audits to ensure protocol safety
• Research and evaluate new blockchain technologies, protocols and DeFi primitives for integration
• Contribute to incident response and debugging of on-chain issues

Required profile

• Strong experience building and deploying production smart contracts on major blockchain platforms
• Deep understanding of blockchain architecture, consensus mechanisms and cryptographic principles
• 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 able to explain complex blockchain concepts to cross-functional teams

Nice to have

• Production experience with multiple blockchain ecosystems (Ethereum, Solana, L2s)
• Previous work at a crypto startup or Web3 infrastructure company
• Experience with cross-chain bridges, oracles or interoperability protocols
• Background with high-volume DeFi protocols or DEX infrastructure
• Open source contributions or formal verification / advanced testing framework experience