Senior Software Engineer (Frontend, Growth)

At WHOOP, we're on a mission to unlock human performance and healthspan. WHOOP empowers members to perform at a higher level through a deeper understanding of their bodies and daily lives. Our wearable technology and digital experiences translate complex physiological data into clear, personalized insights that help members improve their fitness, health, and recovery. The Growth Team at WHOOP is a fast-paced, experimentation-driven group focused on driving user acquisition, activation, engagement, and retention. As a Senior Software Engineer on the Growth team, you will own and drive the technical direction of our web experiences, including our join flow, checkout, and shop that directly impact conversion, revenue, and member engagement. You will lead cross-functional initiatives from technical planning through rollout, mentor engineers across the team, and shape the architecture and practices that allow Growth to move quickly and confidently at scale. Own the architecture and technical direction of WHOOP's web experiences, including our Next.js-based join flow, Cloudflare Workers edge infrastructure, and Stripe-powered checkout Lead cross-functional projects end-to-end from brainstorm and technical planning through implementation, QA, rollout, and post-launch analysis, partnering closely with Product, Design, and Analytics Design and execute experiments (A/B tests) with rigor, ensuring proper instrumentation, measurement, and iteration based on impact to North Star metrics Drive frontend performance, accessibility, and reliability across devices and browsers, establishing standards and monitoring that the team can build on Write clean, well-tested, production-quality code in TypeScript/React/Next.js and integrate deeply with backend services, payment systems (Stripe), and ecommerce platforms (CommerceTools) Author and review technical plans, identify architectural tradeoffs, and make sound judgment calls that balance speed with long-term maintainability Mentor and develop other engineers through code review, pairing, and technical guidance, raising the bar for quality and velocity across the web surface Participate in on-call rotations and incident response; lead postmortems and drive improvements that prevent recurrence Contribute to Growth's engineering culture through documentation, process improvements, and knowledge sharing 5+ years of professional experience in frontend software engineering, with deep expertise inTypeScript, React, and modern web frameworks (Next.js strongly preferred) Track record of owning and delivering complex, cross-functional web projects from technical design through production rollout Strong understanding of web performance optimization, edge computing (e.g., Cloudflare Workers), and responsive design at scale Experience integrating frontend applications with payment systems (Stripe preferred), RESTful APIs, and third-party platforms Demonstrated ability to design and run meaningful A/B tests and make data-informed decisions in a growth or product engineering context Experience with observability and monitoring tools (e.g., Datadog, Sentry, Amplitude) to proactively identify and resolve production issues Proven ability to mentor engineers, lead technical discussions, and influence engineering practices across a team Excellent written and verbal communication skills; comfortable operating in an async-first, cross-functional environment Bonus: Experience with ecommerce platforms (CommerceTools), feature flag / experimentation infrastructure, or subscription/membership business models Learn more about our Software Org and how to be successful in your engineering career at WHOOP via our Career Framework . This role is based in the WHOOP office located in Boston, MA. The successful candidate must be prepared to relocate if necessary to work out of the Boston, MA office. Interested in the role, but don’t meet every qualification? We encourage you to still apply! At WHOOP, we believe there is much more