Principal Backend Developer

COMPANY DESCRIPTION

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.

THE ROLE

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.

KEY RESPONSIBILITIES

• 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 DevOps, troubleshooting, or other platform needs when necessary.

PROFESSIONAL EXPERIENCE & QUALIFICATIONS 

• 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, TypeScript, HTML, and CSS (TailwindCSS or similar). 
• Solid understanding of JavaScript (ES6+), modern browser APIs, RESTful APIs, GraphQL, and WebSockets. 
• 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).

Nice to Have 

• 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.

ABOUT FLAGSHIP PIONEERING:

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 business strategies and has been twice named to Fast Company’s annual list of the World’s Most Innovative Companies. Learn more about Flagship at www.flagshippioneering.com.

At Flagship, we accept impossible missions to enable bigger leaps. Our core values guide us through uncertainty and toward lasting impact.

 

We are an equal opportunity employer. All qualified applicants will be considered for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, protected veteran status, or any other characteristic protected by law.

We recognize that great candidates often bring unique strengths without fulfilling every qualification. If you have some of the experience listed above but not all, please apply anyway. We are dedicated to building diverse and inclusive teams and look forward to learning more about your background and interest in Flagship.

Recruitment & Staffing Agencies: Flagship Pioneering and its affiliated Flagship Lab companies (collectively, “FSP”) do not accept unsolicited resumes from any source other than candidates. The submission of unsolicited resumes by recruitment or staffing agencies to FSP or its employees is strictly prohibited unless contacted directly by Flagship Pioneering’s internal Talent Acquisition team. Any resume submitted by an agency in the absence of a signed agreement will automatically become the property of FSP, and FSP will not owe any referral or other fees with respect thereto.

The salary range for this role is $152,000 - $209,000. Compensation for the role will depend on a number of factors, including a candidate’s qualifications, skills, competencies, and experience. Extuitive, Inc. currently offers healthcare coverage, annual incentive program, retirement benefits and a broad range of other benefits. Compensation and benefits information is based on Extuitive, Inc.'s good faith estimate as of the date of publication and may be modified in the future.