Extuitive, Inc Cambridge, MA Principal Backend Developer

Extuitive is a Flagship Pioneering–backed startup reimagining product innovation for the AI era. Our mission is to empower entrepreneurs and direct-to-consumer (D2C) brands with AI-driven tools that simplify, accelerate, and scale the launch of new products. Based in Cambridge, MA, we operate like a special ops unit—fast-moving, data-driven, and relentlessly focused on impact.

As a Principal Backend Engineer
, you’ll be a technical leader responsible for architecting, building, and scaling the core backend systems that power our platform. You’ll drive the design of high-throughput services, resilient data pipelines, and integrations with mission‑critical third‑party providers. Working closely with product managers, designers, and engineering leadership, you’ll translate complex requirements into robust, elegant systems that support rapid growth. You’ll mentor engineers, influence long‑term technical strategy, and help evolve our platform architecture to maintain security and reliability as we scale.

• Own Core Backend Systems – Design, build, and maintain scalable services, APIs, and platform infrastructure. Ensure reliability, observability, and maintainability.
• Drive Large-Scale Data Pipelines – Architect and operate high‑volume, resilient data pipelines for ingestion, transformation, and analytics.
• Lead Third-Party Integrations – Build and maintain integrations with external vendors, ensuring reliability, observability, and long‑term maintainability.
• Influence Architecture & Best Practices – Shape backend architecture, coding standards, testing frameworks, CI/CD pipelines, and operational excellence.
• Mentor & Lead Engineers – Provide guidance on system design, debugging at scale, and engineering practices.
• Wear Multiple Hats – Support Dev Ops, troubleshooting, or other platform needs when necessary.

• 5+ years of professional front-end development experience.
• Bachelor’s degree in Computer Science, Software Engineering, or equivalent practical experience.
• Strong expertise in React
  , Next.js
  , Type Script ,
  HTML
  , and CSS (Tailwind
  
  CSS or similar).
• Experience with front-end performance optimization techniques such as lazy loading
  , code splitting
  , and caching
  .
• Advanced Figma usage (Dev Mode, Variables, Component Properties, Auto Layout, Variants) and clean handoff from prototypes to code with measurable parity.
• Mastery of adaptive layout techniques (Container Queries, CSS Grid/Flex, fluid type/spacing) across breakpoints and device classes.
• Proficiency with modern animation libraries (e.g. Framer Motion, React Spring, GSAP).
• Comfortable working in a fast‑paced startup environment with evolving priorities and minimal oversight.
• Familiarity with frontend build pipelines and code hygiene best practices (e.g. linting, test coverage, pre‑commit checks, etc.)
• Building and maintaining a documented component library in Storybook (or other framework).

• Exposure to AI frontend tools like AI SDK
  , Assistant UI
  , or comparable interactive agent interfaces.
• Experience with Supabase or other modern databases.
• Experience implementing async patterns in complex design systems.
• Familiarity with Google Cloud Platform (GCP),
  AWS and Vercel for deployment and cloud workflows.
• Experience operationalizing design tokens from Figma Variables into code (Style Dictionary/CSS variables), keeping Figma and the design system in sync.

Flagship Pioneering invents and builds platform companies, each with the potential for multiple products that transform human health, sustainability and beyond. Since its launch in 2000, Flagship has originated more than 100 companies. Many of these companies have addressed humanity’s most urgent challenges: vaccinating billions of people against COVID-19, curing intractable diseases, improving human health, preempting illness, and feeding the world by improving the resiliency and sustainability of agriculture.

Flagship has been recognized twice on FORTUNE’s “Change the World” list, an annual ranking of companies that have made a positive social and environmental impact through activities that are part of their core…