Backend Engineer

**Fun.xyz** Backend Engineer (Mid–Staff); $120–300k across L1–L4 + equity; Midtown NYC HQ preferred (Singapore considered for a small subset of team members)

**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** The Backend Engineering team designs and operates the high-performance systems that power Checkout and Fun.xyz’s broader payments stack. Backend Engineers architect APIs, services, and distributed systems that handle payments, settlement, asset conversion, identity/security verification, and multi-chain transaction routing. This is a foundational role in building fault-tolerant, low-latency infrastructure that can scale globally while meeting security and compliance expectations. You will report into the CTO (ex-Hyperlane, ex-Uniswap) and work closely with product engineers and protocol engineers.

**Responsibilities** - Design, build, and maintain high-performance APIs and backend services for Fun.xyz’s Web3 payments platform. - Implement and evolve systems for payments, settlement, transaction routing, asset conversion, and identity/security flows across chains and providers. - Build new backend features that improve product experience, conversion, and reliability for dApps and partners. - Participate in system design, architecture reviews, and incident response to ensure reliability, scalability, and fault tolerance. - Write clean, well-tested code and contribute to code reviews and engineering standards.

**Required Skills** A. Strong experience building production backend systems in a modern language (TypeScript preferred; Go or Rust acceptable for strong system engineers willing to work in TS). B. Proficiency with TypeScript or clear ability and motivation to ramp quickly (core stack). C. Deep understanding of distributed systems, APIs, and database design principles. D. Hands-on experience with cloud platforms and containerization (e.g., Docker, Kubernetes, modern cloud infra). E. Solid CS fundamentals in algorithms, data structures, and systems design.

**Bonus Skills** - Experience in payments, fintech infrastructure, or transaction-heavy consumer apps. - Prior exposure to blockchain integrations, smart contracts, or DeFi protocols (not a hard requirement). - Familiarity with event-driven architectures and real-time data processing. - Contributions to open source or technical writing in backend, infra, or crypto domains. - Strong crypto knowledge required; candidates with low crypto knowledge will not pass.

**Logistical Info** - **Location:** Midtown NYC HQ preferred; in-person Mon–Thu, optional remote Friday. Singapore considered only for Singapore Nationals due to current entity limitations. - **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; senior backend/EM profiles can approach the top end of the band (exact band confirmed per candidate level). - Number of openings: 1 - **Other:** H‑1B transfers and US domestic relocation are supported for US candidates (candidates must have held H-1B for more than 12 months to be eligible for transfer); international relocation and new visas are case-by-case; only Singapore Nationals can currently work from Singapore due to entity setup

**Ideal Background** - Backend/system engineers from high-scale fintechs, infra companies, or consumer apps with experience in payments, routing, or transactional systems. - Crypto/Web3 backend engineers with strong infra chops who can operate in TypeScript and distributed architectures.

**Green Flags** - Strong backend engineer (not DevOps-leaning) - Payments / fintech experience (not cloud/AWS-heavy big-tech without payments) - US- or Singapore-based with long-term work authorization (Singapore nationals; H-1B / STEM-OPT with >12 months remaining)

**Red Flags** - Pure front-end profiles without substantial backend ownership. - Strongly remote-only candidates unwilling to commit to regular NYC in-office presence. - Shallow systems design or weak fundamentals, especially under time-boxed live coding. - Candidates requiring new H-1B sponsorship or with less than 12 months on H-1B visa. - Candidates unwilling to relocate or work in NYC or Singapore as required. - Lack of strong motivation aligned with company mission and product focus.

**Interview Process** 1. Recruiter screen with Recruiter 2. 1-hour live coding interview with CTO or senior backend engineer using a shared environment (e.g., CodeSandbox/HackerRank); candidates can choose language, but mainstream languages fare better. 3. Follow-up systems design / technical deep-dive. 4. Onsite in NYC for additional coding and technical interviews (~2 hours) plus potential founder chat.