Senior Backend Engineer

As a Senior Backend Engineer, you’ll design, build, and scale core backend systems that power high-traffic consumer products and internal platforms. You’ll own foundational services and APIs, work on high-throughput distributed systems, and partner closely with product, ML, and engineering teams to deliver reliable, low-latency experiences at scale.

Phia has raised $43M from Notable Capital, Khosla Ventures, and Kleiner Perkins, with backing from founders and operators like Vlad Tenev (Robinhood), Mellody Hobson (Ariel Investments), Naomi Gleit (Meta), and Mati Staniszewski (ElevenLabs), plus a roster of cultural leaders, to build the AI alignment layer for commerce. In just over a year, Phia's consumer shopping agent has surpassed 1.5 million users and partnered with 9,600+ retail brands across contemporary, resale, and luxury, representing billions in annual gross merchandise volume. We scan more than 350 million products to help shoppers find the right pieces at the best price, cutting return rates by 50%, and we're on pace for nine-figure sales growth this year.

In an era where AI vertical agents are reshaping every industry, commerce is on the verge of a complete transformation. Phia is reinventing shopping from a fragmented, impersonal experience into one that feels intelligent, trusted, and built around each user's intent. This foundation of trust is our wedge to become the end-to-end shopping destination for the next generation of buyers.

Phia is a lean, high-ownership team building at startup speed. If you want to ship at high velocity and solve complex problems in consumer AI and commerce, this is the place to do it.

• Design and build scalable backend services, APIs, and shared platform components

• Own system architecture, performance, and reliability for core backend systems

• Partner with product and ML teams to support data- and model-driven workflows

• Improve observability, monitoring, and operational best practices

• Drive technical decisions and contribute to long-term platform strategy

• Raise the quality bar through code reviews, design discussions, and mentorship

• 3+ years of experience building and operating backend systems in production

• Strong experience with APIs, databases, and distributed systems

• Proficiency in at least one backend language and modern backend frameworks

• Experience designing systems for scale, performance, and reliability

• Strong ownership mindset and ability to work in fast-moving environments

• Clear communicator who collaborates well across functions