Protocol Engineer

**Fun.xyz** Protocol Engineer; $120–300k across L1–L4 + equity; Midtown NYC HQ preferred, Singapore considered

**About Company** Fun.xyz builds crypto payment infrastructure that makes onchain value transfer intuitive, secure, and seamless for everyday users and developers. Its flagship product, Checkout, is a high-conversion payment solution that lets users complete any onchain action using assets from self‑custodial wallets, centralized exchanges, or on-ramped fiat from cards and bank accounts. By aggregating routing and exposing users’ full asset portfolios at the point of sale, Checkout helps dApps drive faster, stickier, more engaged users without stitching together multiple providers or spinning up new chains. If you believe anyone, anywhere should be able to purchase anything with any asset, Fun.xyz is a place to build that future

**About the Role** Fun.xyz is expanding its core blockchain team with a Protocol Engineer who can help define the foundation of its Web3 payments infrastructure. This is a high-impact role at the intersection of smart contracts, cross-chain protocols, and DeFi, focused on secure and efficient onchain systems that enable millions of transactions across multiple networks. You will be “another version” of Fun’s existing Solidity engineer: deeply crypto-native, comfortable owning protocol design and implementation, and able to collaborate closely with backend and product teams.

**Responsibilities** - Design, develop, and deploy secure smart contracts and protocol components across multiple blockchain platforms. - Architect blockchain solutions for payments and settlement in collaboration with backend and product teams, translating business requirements into robust onchain designs. - Write highly efficient, well-tested contract code and participate in internal and external security reviews. - Research and evaluate new chains, DeFi primitives, and interoperability protocols for potential integration into Checkout. - Support incident response and debugging of onchain issues to ensure protocol reliability.

**Required Skills** A. Proven experience building and deploying production smart contracts on major blockchain platforms (e.g., Ethereum/L2s). B. Hands-on expertise with one or more smart contract languages: Solidity (preferred), plus Rust or Move a strong plus. C. Solid grasp of DeFi protocols, token standards, and cross-chain communication patterns. D. Strong security mindset, including awareness of common smart contract vulnerabilities and best practices.

**Bonus Skills** - Deep understanding of blockchain architecture, consensus mechanisms, and applied cryptography concepts used in smart contract systems. - Production experience across multiple ecosystems (L1s and L2s), including non-EVM chains. - Familiarity with cross-chain bridges, oracles, and interoperability frameworks. - Experience with formal verification or advanced contract testing frameworks (e.g., Foundry, Echidna). - Contributions to open-source blockchain projects or protocol research

**Logistical Info** - **Location: **Midtown NYC HQ preferred; in-person Mon–Thu, optional remote Friday. Singapore considered for a small subset of team members. - **Compensation:** Fun.xyz targets roughly 75th percentile of market base comp with a broad band from ~120–300k across L1–L4, with equity scaled by level - Number of openings: 1 - **Other:** H‑1B transfers and US domestic relocation are supported; international relocation and new visas are case-by-case.

**Ideal Background** - Senior blockchain engineers with deep Solidity/EVM production experience at leading protocols or infra projects, with clear mainnet ownership. - Crypto-native engineers who have designed and shipped core DeFi or payments contracts and can engage collaboratively with product and backend teams.

**Green Flags** - Track record at recognized protocol / crypto teams - Reliable follow-through (attends scheduled interviews)

**Red Flags** - Candidates with primarily tutorial/hackathon experience and no meaningful mainnet deployments. - Candidates from unfamiliar / unrecognizable companies - Pure “DeFi tourist” profiles without evidence of protocol depth or security rigor. - Security/audit-only profiles without evidence of mainnet smart contract ownership do not qualify. Audit experience alone is not a substitute for protocol depth

**Interview Process** 1. Recruiter screen with Caroline to confirm technical depth, location, and compensation expectations. 2. Hiring manager technical screen with existing Solidity engineer and/or protocol lead (deep dive on past work). 3. Technical assessments on smart contract design, code review, and security thinking (live and/or take-home). 4. Onsite in NYC for broader technical and culture interviews; potential founder/CTO session.