Senior Software Engineer, Front End

About the Role

The Pioneering Intelligence group at Flagship Pioneering is building intelligent software systems that integrate agentic AI with scientific reasoning to accelerate research, development, and decision‑making.

We are seeking a Senior Front‑End Software Engineer to design, integrate, and deploy web‑based applications that enable seamless human–AI collaboration. This role is part of a bold, agentic initiative within the Pioneering Intelligence portfolio and offers the opportunity to help define the future of user‑centric, LLM‑enabled platforms.

Flagship Pioneering is a biotechnology company that invents and builds platform companies, each with the potential for multiple products that transform human health and sustainability. Since its founding in 2000, Flagship has launched and fostered more than 100 scientific ventures, collectively generating over $90 billion in aggregate value. Many of these companies have addressed humanity’s most urgent challenges—vaccinating billions against COVID‑19, curing intractable diseases, improving human health, preempting illness, and strengthening global food security.

Flagship has twice been recognized on Fortune’s “Change the World” list and twice named to Fast Company’s “World’s Most Innovative Companies.” Learn more at

As a key contributor in this early‑stage initiative, you will architect and implement the user experience for a new platform that leverages large language models (LLMs) and AI agents to enhance complex, high‑stakes workflows.

This is a user‑, AI‑augmented product—your work will transform abstract reasoning tasks into intuitive, high‑performance tools that empower experts across diverse research domains.

You will lead front‑end development and collaborate closely with engineers, AI scientists, product designers, and end users. This is a rare opportunity to shape a greenfield product at the intersection of usability, flexibility, and advanced reasoning.

• Architect, develop, and maintain high‑quality, testable front‑end code and workflows aligned with complex scientific and analytical use cases.
• Translate user stories, wireframes, and prototypes into production‑ready features emphasizing clarity, maintainability, and reusability.
• Implement responsive, accessible, and performant UIs optimized for data‑rich, interactive workflows.
• Ensure security, scalability, and observability of front‑end services in cloud environments (AWS).
• Design and implement user interfaces from scratch, combining strong visual design with robust engineering.
• Create and maintain scalable, consistent, and visually appealing UI components using a modern React.js stack.
• Maintain front‑end quality through comprehensive testing and validation of user flows and interface behavior.
• Develop and maintain test suites (unit, integration, and end‑to‑end) for UI reliability.
• Apply Dev Ops/Git Ops practices for automated testing, deployment, and monitoring.
• Mentor engineers and scientists, driving technical quality and ensuring extensibility and performance across evolving use cases.

• B.S. in Computer Science, Engineering, or related field, with 6+ years of professional software development experience.
• Expertise with modern front‑end frameworks and tools, including React.js, Type Script, Tailwind CSS, Redux Toolkit, Playwright, and Shadcn.
• Strong experience with Node.js.
• Skilled in writing and maintaining comprehensive test suites (Jest, React Testing Library, Cypress).
• Experience with system design, performance optimization, observability, and operational excellence for parallel LLM workloads.
• Strong intuition for UX design and a passion for building intuitive, workflow‑first products.
• Excellent communication skills and a collaborative mindset in fast‑moving, cross‑functional environments.

• Background in scientific domains such as biology, chemistry, or complex systems (a plus, not required).

• Help define a new category of intelligent software tools for real‑time human–AI collaboration.
• Build a greenfield product at the intersection of usability, reasoning, and scientific innovation.
• Collabor…