Title: Full Stack Software Engineer Location: Hybrid - LA, NYC, and Austin/Houston area This position has a requirement of 1 week per month in office. About the Role We’re looking for a Full-Stack Software Engineer with a sharp eye for UI/UX and a robust back-end mindset to help us build exceptional ecommerce experiences across web and mobile. You’ll architect and implement features from the database to the browser, working closely with design, growth, and product teams to bring our digital vision to life. This includes everything from high-converting PDPs and seamless subscription flows to the powerful APIs and services that drive them. This role is for someone who thrives in a fast-moving environment, loves clean code, and thinks like a customer from end to end. If you have deep experience across the stack, love solving complex technical challenges, and want to push the boundaries of DTC commerce — this role is for you. What You’ll Be Doing Build & Ship End-to-End Features • Develop and maintain scalable front-end features across our Shopify storefront using Shopify Hydrogen, Shopify Themes, and React.js. • Architect, build, and maintain server-side logic and APIs using Node.js and/or Ruby. • Design and manage our data layer, working with databases like Firebase and Postgres. • Own reusable component libraries and design systems using React, SCSS/CSS, and Shopify Polaris. • Integrate and manage data flows between the Shopify Admin, Storefront, and AJAX Cart APIs. Optimize for Speed, Scale & Conversion • Continuously improve full-stack performance, from database query efficiency to page speed and interaction responsiveness. • Implement and support A/B testing and personalization, ensuring robust back-end functionality for front-end experiments. • Translate Figma files and performance briefs into fast, pixel-perfect, and production-ready code built on a scalable architecture. • Develop custom back-end solutions to support retention, loyalty, and subscription programs. Cross-Functional Collaboration & Architecture • Work across business units with stakeholders to create seamless integrations with APIs, apps, and data sources. • Partner with marketing and growth teams to build rapid-test landing pages that are deeply integrated with our back-end services. • Own the implementation of server-side analytics, event tracking, and data warehousing integrations. • Define and evolve the core architecture of our ecommerce platform for long-term scalability and performance. Who You Are • 5+ years of full-stack development experience, ideally in a fast-moving DTC ecommerce environment. • Deep experience with the Shopify ecosystem, including Shopify Themes, Shopify Liquid, Shopify Hydrogen, and the Shopify Admin, Storefront, and AJAX Cart APIs. • Expertise in front-end technologies including JavaScript (JS), HTML, SCSS/CSS, and React.js. • Proficiency in back-end development with Node.js or Ruby. • Experience designing and managing databases with Firebase and/or Postgres. • Familiarity with building and maintaining component libraries, especially with Shopify Polaris. • Strong understanding of responsive design, UX best practices, and full-stack performance optimization. • Familiar with A/B testing platforms (e.g., Convert, VWO, PostHog) and analytics tagging (GA4, Triple Whale, Segment). • Proactive communicator who thrives in async, cross-functional teams. Why This Role is Different • You’ll ship real features — not just tickets • Your work directly impacts CVR, AOV, and customer experience across channels • Fast feedback loops — growth, creative, and UX teams are your close collaborators • Real ownership — we don’t micromanage; we hire builders • Work on a highly-visible, high-traffic ecommerce site with a 9-figure brand behind it How to Stand Out • Show us sites you’ve built or pages you’ve optimized (especially on Shopify or headless stacks) • Share your GitHub, portfolio, or a project you’re proud of — bonus for ecommerce or performance UX • Tell us about a complex feature you architected that moved the needle on performance, scalability, or user experience. If you’re a builder at heart who cares about clean UI, fast code, and customer-first web experiences — we’d love to connect. About First Day: First Day stands at the forefront of health and wellness, driven by a passion for empowering families to live their healthiest, most vibrant lives. Guided by cutting-edge research, we’ve created a lineup of science-backed products designed to foster total well-being. By championing innovative solutions for every stage of life, First Day remains steadfast in our commitment to helping individuals and families unlock their full potential for health and vitality. Discover more about First Day and explore their product line at www.firstday.com. First Day participates in E-Verify to confirm the employment eligibility of all newly hired employees. As part of the I-9 verification process, we use E-Verify to ensure that candidates are legally authorized to work in the United States. For more information about E-Verify, please visit the E-Verify website.