Backend Software Engineer, CoreApp

About OnePay

OnePay is the consumer fintech trusted by millions of Americans to make money better.

Our financial system is broken. High fees, low rates, and too few ways to actually grow your money. We’re fixing it. And we’re moving fast.

We’re an all-in-one financial services platform that brings together banking, high-yield savings, credit cards, point-of-sale lending, investing, and crypto in one place. We also partner with employers, HCM providers, gig platforms, and others to deliver embedded financial services to millions of employees and frontline workers.

We’re backed by Walmart, the world’s largest retailer, and Ribbit Capital, one of fintech’s most respected investors, giving us rare scale, distribution, and the opportunity to build something truly category-defining.

But what really sets OnePay apart is how we move. Our customers don’t have time to wait… and neither do we. This place moves fast, and we’re looking for people who are:

• Ready to run

• Hungry and driven by urgency

• Exceptional at what they do, with low ego

• Comfortable operating in motion

The Role

As a Backend Software Engineer on the Core App team at OnePay, you will build backend systems that directly power our mobile and web user experience. You will:

• Design, build, and ship backend services that support user-facing features across mobile and web experiences

• Collaborate closely with frontend engineers, product managers, designers, and data partners

• Lead backend technical planning and contribute to architecture decisions that improve scalability, reliability, and performance

• Proactively identify opportunities to improve user experience through backend optimizations and system enhancements

• Build and maintain clear technical documentation to support a growing and distributed engineering organization

You Bring

• 5+ years of professional experience building and scaling backend systems in consumer technology or fintech environments

• Experience designing and operating distributed systems, APIs, and data flows that support user facing applications

• Familiarity with message brokers and event driven systems, as well as caching and performance optimization strategies

• Demonstrated ability to lead technical execution, mentor other engineers, and deliver with a high bar for quality

• Drive and proactivity – everyone here is a builder and executor.

Tools We Use

We use the fp-ts library for functional programming with Node/TypeScript running on top of Kubernetes and AWS. We believe great engineers can learn any stack, so you do not need experience with these specific tools, but you’ll ramp up more quickly if you are familiar with functional programming concepts.

What We Offer

• Competitive base salary, stock options, and health benefits from Day 1

• 401(k) plan with company match

• Remote-friendly (US), flexible time off (FTO), and opportunities for growth

• A high-growth, mission-driven, inclusive culture where your work has real impact

Standard Interview Process

• Initial Interview with Talent Partner

• Technical or Hiring Manager Interview

• Team Interview

• Executive Interview

• Offer!

Equal Employment Opportunity

To build technology and products that are used and loved by people and solve real-world problems, we need to build a team with many different perspectives and experiences. We are an equal opportunity employer. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status. We encourage candidates from all backgrounds to apply. Applicants in need of special assistance or accommodation during the interview process or in accessing our website may contact us at talent@onepay.com.