Senior Backend Developer

Company Overview

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.

About the Role  

As a senior backend engineer, you will be instrumental in delivering architecture improvements that will scale our platform.  You’ll collaborate closely with product managers, designers, and other engineers to translate complex requirements into elegant, responsive, and performant interfaces. Beyond building, you’ll set standards, mentor peers, and play a key role in scaling both our product and our engineering practices. Specifically, you will:  

Responsibilities

• Build and Scale the Core Infrastructure - Design and implement the foundational backend architecture (APIs, databases, services) 
• Own End-to-End Backend Features - Translate product requirements into backend solutions — from data modeling to API design to deployment. 
• Collaborate Closely with Product & Frontend - Partner with product managers and frontend engineers to deliver user-facing functionality that feels seamless.  
• Handle Data & Integrations - Own the data layer (schema design, migrations, query optimization),  
• Introduce coding standards, testing practices, CI/CD pipelines, and monitoring/observability from the start. 

Requirements 

• 5+ years of professional back-end development experience 
• Bachelor’s degree in Computer Science, Software Engineering, or related field (or equivalent experience) 
• Expertise in back-end technologies, including Python, Node.js, FastAPI, and Supabase 
• Strong knowledge of databases: schema design, query optimization, and performance tuning 
• Familiarity with DevOps practices, including CI/CD pipelines, monitoring, logging, and observability tools 
• Experience building real-time systems (e.g., WebSockets, data streaming) and/or AI/ML-powered applications 
• Commitment to clean, maintainable code and a passion for establishing best practices 
• Thrives in fast-paced startup environments, with adaptability to shifting priorities 

More About Flagship Pioneering

Flagship Pioneering is a bioplatform innovation company that invents and builds platform companies, each with the potential for multiple products that transform human health or sustainability. Since its launch in 2000, Flagship has originated and fostered more than 100 scientific ventures, resulting in more than $90 billion in aggregate value. Many of the companies Flagship has founded 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.

Flagship Pioneering and our ecosystem companies are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity or Veteran status.

At Flagship, we recognize there is no perfect candidate. If you have some of the experience listed above but not all, please apply anyway. Experience comes in many forms, skills are transferable, and passion goes a long way. We are dedicated to building diverse and inclusive teams and look forward to learning more about your unique background.

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.