Principal Backend Developer

About 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.

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
• 8+ years of backend engineering experience.
• Bachelor's degree in Computer Science, Software Engineering, or equivalent practical experience.
• Strong expertise in backend languages and frameworks (Node.js/TypeScript, Go, Python, or similar).
• Experience designing scalable distributed systems, microservices, and event-driven architectures.
• Deep experience with third-party integrations, REST/GraphQL APIs, webhooks, and rate-limited services.
• Proficiency with SQL/NoSQL databases, data pipelines, and performance optimization.
• Familiarity with cloud platforms (AWS, GCP) and containerized/deployed systems (Docker, Kubernetes).
• Strong testing, CI/CD, and observability practices.
• Comfortable working in a fast-paced, evolving environment with minimal oversight.

Requirements

• Experience building and shipping features quickly in early-stage startups.
• Exposure to multiple backend domains (analytics, payments, notifications, workflow orchestration).
• Hands-on experience with serverless or edge architectures for rapid iteration.
• Familiarity with low-friction integrations with third-party tools and SaaS platforms.
• Track record of scaling systems from small MVPs to production-ready services.
• Comfort with ambiguity and making trade-offs between speed, quality, and maintainability.
• ABOUT FLAGSHIP PIONEERING:
• 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.
• Recruitment & Staffing Agencies : Flagship Pioneering and its affiliated Flagship Lab com

Benefits

Additional Information

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.

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