Protocol Engineer, San Francisco

As a Protocol Engineer at Fun, you join the core blockchain team building the foundation of Web3 payments infrastructure. You'll design and implement secure, efficient smart contract systems and blockchain integrations that power millions of transactions across multiple chains, working at the intersection of smart contracts, cross-chain protocols, and decentralized finance.

What you'll do

• 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

What you bring

• 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 such as Solidity, Rust, or Move
• A solid grasp of DeFi protocols, token standards, and cross-chain communication patterns
• A strong security mindset with knowledge of common smart contract vulnerabilities and best practices
• Clear communication skills to explain complex blockchain concepts to cross-functional teams

Nice to have

• Production experience with multiple blockchain ecosystems such as Ethereum, Solana, and 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
• Contributions to blockchain open-source projects or protocol research
• Experience with formal verification or advanced smart contract testing frameworks

About Fun

Fun builds the infrastructure powering consumer-facing fintech applications that handle onboarding, account access, and money movement. The company operates at the intersection of financial infrastructure, complex engineering, and product experience, providing fintech builders with an onboarding and deposit stack that drives conversion and unlocks user growth.