Backend Engineer, San Francisco

Capital markets are undergoing a fundamental shift. Assets that live in fragmented systems and manual workflows are moving onto blockchains -systems designed to move and store value more transparently and efficiently.

While this unlocks more open and programmable financial systems, it also introduces significant complexity. For most users, interacting with this new infrastructure is still too difficult.

Fun builds the infrastructure that powers consumer-facing fintech applications - handling onboarding, account access, and money movement so users can interact with blockchain-based systems as seamlessly as they do with traditional finance.

For fintech builders, Fun provides a best-in-class onboarding and deposit stack that drives conversion and unlocks user growth. We operate at the intersection of financial infrastructure, complex engineering, and product experience.

About the Role We’re looking for a BackEnd Engineer to join our growing team at Fun and help architect the backend services that power our web3 payments infrastructure. This role is foundational to the success of our platform and will shape how payments, settlement, and transaction routing are handled across chains and payment providers. You’ll be working on high-performance, low-latency systems that support complex use cases like asset conversion, identity and security verification, transaction finality, and decentralized routing—while ensuring fault tolerance, scalability, and compliance across a global user base.
Team: Payments Infrastructure – Mid, Senior, Staff, or Principal Levels

Responsibilities

Design, build, and maintain high-performance APIs and backend services that power our Web3 payments platform

Build new features to further our product experience

Collaborate with product and protocol teams to architect technical solutions that meet business requirements

Write clean, well-tested code and participate in code reviews to maintain high engineering standards

Contribute to incident response and debugging production issues to ensure system reliability

Requirements

Strong experience building production backend systems with modern languages

Proficiency in Typescript

Deep understanding of distributed systems, APIs, and database design principles

Hands-on experience with cloud platforms and containerization technologies

Solid grasp of computer science fundamentals including data structures and algorithms

Strong problem-solving skills with ability to debug complex technical issues

Clear communicator who can collaborate effectively with cross-functional teams

Nice to Have

Production TypeScript experience

Previously worked at crypto startup or Web3 infrastructure company

Experience with blockchain integrations, smart contracts, or DeFi protocols

Background with high-scale payment processing or financial compliance systems

Contributions to open source projects or technical writing

Experience with event-driven architectures and real-time data processing

Why Join Us ● Shape the future of payments and programmable money ● Work with bleeding-edge tech in a domain where innovation moves fast ● Join a mission-driven team focused on access, openness, and trust ● Be a key contributor, not just a cog—your work will ship fast and matter ● Collaborate with top-tier protocols, builders, and financial infrastructure providers Location and Work Environment This role is primarily in-person at our Midtown, NYC headquarters. We work together Monday through Thursday for fast, iterative collaboration and optional WFH Fridays to reset and recharge.