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Flagship Pioneering · 1 month ago

Principal Backend Developer

Cambridge, MA USA

Full-time

Onsite

Senior Level, Lead/Staff

$152K/yr - $209K/yr

5+ years exp

Extuitive is a Flagship Pioneering–backed startup reimagining product innovation for the AI era. 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, while mentoring engineers and influencing long-term technical strategy.

FinanceFinancial ServicesVenture Capital

H1B Sponsor Likely

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

Qualification

Backend Systems DesignData Pipeline ArchitectureAPI DevelopmentReactTypeScriptJavaScript (ES6+)Mentoring EngineersFrontend Performance OptimizationFigma UsageComponent Library MaintenanceFast-Paced Environment

Required

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)

Preferred

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

Benefits

Healthcare coverage

Annual incentive program

Retirement benefits

Broad range of other benefits

Company

Flagship Pioneering

Glassdoor3.3

Flagship Pioneering is a venture capital firm that invests in life sciences and healthcare companies.

Founded in 2000

Cambridge, Massachusetts, USA

501-1000 employees

http://flagshippioneering.com

H1B Sponsorship

Flagship Pioneering has a track record of offering H1B sponsorships. Please note that this does not guarantee sponsorship for this specific role. Below presents additional info for your reference. (Data Powered by US Department of Labor)

Distribution of Different Job Fields Receiving Sponsorship

Represents job field similar to this job

Trends of Total Sponsorships

2025 (8)

2024 (4)

2023 (4)

2022 (4)

2021 (1)