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Flagship Pioneering · 4 hours ago

Senior Frontend Developer

Cambridge, MA

Full-time

Onsite

Mid, Senior Level

$108K/yr - $176K/yr

5+ years exp

Flagship Pioneering is a startup focused on reimagining product innovation for the AI era. As a Senior Frontend Engineer, you will design and build the user experience of the platform while collaborating with product managers, designers, and backend engineers, and also mentor peers and set standards in engineering practices.

FinanceFinancial ServicesVenture Capital

H1B Sponsor Likely

Responsibilities

Own the End-to-End Frontend - Translate designs (Figma, wireframes, product specs) into production-ready code. Build and maintain reusable components, design systems, and UI patterns for speed and consistency

Drive Technical Quality & Best Practices - Introduce testing frameworks (unit, integration, E2E) and enforce high code quality. Establish frontend best practices (linting, CI/CD pipelines, accessibility standards)

Influence Architecture & Tech Choices - Make early decisions around frameworks, state management, styling systems, and frontend tooling. Advocate for the right balance of speed vs. scalability in architecture choices

Wear Multiple Hats - Jump in on DevOps, analytics, or even light backend integration when needed. Help with customer-facing issues (debugging, bug fixes, UI polish) in real time

Qualification

ReactNext.jsTypeScriptHTMLCSSJavaScript (ES6+)RESTful APIsGraphQLWebSocketsFigmaPerformance optimizationAdaptive layout techniquesAnimation librariesFrontend build pipelinesComponent libraryAI frontend toolsSupabaseAsync patternsGoogle Cloud PlatformAWSVercelDesign tokens

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)