How You Will Make an Impact ThredUp is reshaping how the world thinks about secondhand fashion. As a Senior Back-End Engineer (Core E-comm), you’ll take ownership of the systems that power our buyer experience, from seamless onboarding to checkout and returns. At ThredUp’s scale, your work won’t just ship features; it will influence architecture, raise engineering standards, and directly impact millions of customers discovering sustainable fashion every day. You’ll work within our Ruby monolith and adjacent microservices, balancing improvements to mature systems with forward-thinking modernization efforts. You’ll have the opportunity to drive long-term architectural enhancements in distributed systems, event-driven design, and service decomposition. Beyond technical execution, you’ll collaborate across product, design, and data science, ensuring engineering efforts align with both customer needs and business goals.
In This Role, You Will ● Drive technical direction for core commerce services, balancing short-term delivery with long-term scalability. ● Take ownership of critical back-end flows, including purchasing, returns, promotions, and notifications. ● Collaborate with cross-functional partners to turn complex problems into simple, elegant solutions. ● Mentor engineers across teams, raising the bar for code quality, testing, and design practices. ● Lead system design discussions and contribute to architectural decisions. ● Experiment with AI-driven developer workflows to accelerate productivity and enhance platform intelligence. ● Own end-to-end initiatives, from architecture through monitoring and iterative improvements.
What We’re Looking For ● 7+ years of professional software development experience, with deep expertise in Ruby on Rails and scaling monolithic applications, including decomposition into services. ● Strong API design skills (REST + GraphQL) and experience supporting high-volume cross-service communication. ● Proficiency in relational databases (MySQL), event-driven systems (Kafka), and background processing (Sidekiq, Redis).
● Experience with containerized deployments (Docker, Kubernetes) and CI/CD workflows. ● Strong communication skills with a track record of driving technical decisions and writing clear documentation. ● A proactive, ownership-driven mindset with comfort working in ambiguous, cross-functional environments. ● Eagerness to learn new domains and contribute across the stack as needed. Bonus Points(Strong Plus / Nice to Have) ● JVM ecosystem experience (Java/Kotlin). ● Front-end or mobile exposure (PWA, iOS/Swift, Android/Kotlin). ● Experience scaling e-commerce or consumer apps with millions of users. ● Proven success leading initiatives, mentoring engineers, and shaping architecture. ● Familiarity with performance monitoring and observability tools. ● Strong product sense, specifically understanding how technical trade-offs affect UX and business outcomes.
Why ThredUp This is an opportunity to shape the technical backbone of a company making fashion more sustainable at scale. You’ll join a team that values ownership, experimentation, and continuous improvement; and, you’ll see the direct impact of your work on millions of customers.
