Flex
Backend Engineer
United States
Sponsorship not specifiedDetected 81 days ago
TypeScriptPythonGoRustNode.jsBackend DevelopmentData StructuresProblem Solving
About the role
- Analyze, troubleshoot, and resolve production issues rooted in business logic, data correctness, and transactional edge cases
- Contribute to a culture of learning, problem-solving, and operational excellence
Responsibilities
- Design, build, and own backend services and APIs that power Flex's applications
- Model the domain - eligibility rules, transactions, merchants, consumer accounts, etc. - in data structures and APIs that other teams build on
- Partner with frontend, design, and business stakeholders to translate merchant and consumer needs into reliable APIs and workflows
- Own and improve our backend service architecture, data models, and integrations
- Collaborate on cross-functional projects that connect the full Flex experience, from consumer checkout to merchant analytics
- Create and maintain documentation for APIs, services, and on-call runbooks
Requirements
- You have 5+ years of experience building production backend services and APIs in a typed language (Rust, TypeScript/Node, Go, Python, etc.)
- You have an execution mindset and always keep the end user in mind
Nice to have
- Experience with building systems using Rust
- Early-stage impact - your work will directly shape our growth and success
- Collaborative, high-trust, and transparent culture
Skills
- You're resourceful, curious, and comfortable learning new tools quickly
- You're proficient at leveraging AI tools to ship faster
Compensation
- With $150 billion in annual HSA/FSA spending potential, we're giving brands the tools to unlock new revenue and making it easier for consumers to use the benefits they've earned.
Benefits
- making it easy for health and wellness brands to accept HSA and FSA payments online.
- For years, only giants like Amazon and Walmart could process these payments at checkout, leaving smaller merchants - and their customers - to deal with frustrating reimbursement paperwork.
- Our technology verifies product eligibility in real time, handles split payments for eligible and non-eligible items, and can even issue Letters of Medical Necessity during checkout.
- With $150 billion in annual HSA/FSA spending potential, we're giving brands the tools to unlock new revenue and making it easier for consumers to use the benefits they've earned.
- We're looking for a Backend Engineer to design and own the services and APIs that power Flex - eligibility verification, split payments, and LMN (letter of medical necessity) issuance at checkout to name a few.
- You'll work closely with frontend engineers, design, and business stakeholders to build reliable systems that move real money correctly and unlock HSA/FSA spending for merchants and consumers.
Company info
- This is a role for someone who thrives in ambiguity, takes initiative, and is excited about building at an early-stage company.
This listing is sourced directly from Flex's careers page and normalized into a canonical job model.