Principal / Senior Software Engineer

The Company  

FL105 is a privately held, early-stage company pioneering the use of artificial intelligence to transform human psychological fitness and wellbeing. We are creating a platform that empowers people to build a life they are proud of and fulfilled by.   

FL105 is backed by Flagship Pioneering, an innovation enterprise that conceives, creates, resources, and builds companies that invent breakthrough technologies that transform the world. Flagship has created over 100 groundbreaking companies since 2000, including Moderna.  

The Role  

We are seeking an experienced, creative, and talented  Principal /  Senior Software Engineer.  The ideal candidate will have a strong background in software and product development, with the ability to lead projects and communicate effectively across teams and with ML researchers.  

Key Responsibilities  

In this role, you will:  

• Lead the design and development of customer-facing features across the front-end and back-end application stack.  
• Partner closely with product managers, designers, and researchers to translate customer needs and product strategy into well-designed, high-impact features.  
• Own features throughout the full product development lifecycle, from discovery and technical design through implementation, release, measurement, and iteration.  
• Manage the release process for new features, including rollout planning, feature flagging, monitoring, and coordination across engineering and product teams.  
• Use product analytics, feature experiments, and customer feedback to evaluate feature performance and guide continued development.  
• Design scalable system architecture for rapidly evolving, AI-enabled back-end components.  
• Contribute to user interface and interaction design, bringing technical insight into product and design decisions.  
• Improve application delivery practices by implementing continuous integration, continuous delivery, automated testing, and operational best practices.  
• Leverage AWS cloud infrastructure to build scalable, reliable, and efficient applications and AI-powered services.  
• Uphold high standards of data security, privacy, and compliance across all applications.  

Successful candidates will be able to thrive in a fast-paced, action-oriented, team environment and display a clear passion for AI innovation and impact. The role offers a unique opportunity to help drive the strategy of an early stage AI-focused company. The candidate must be an entrepreneurial, highly motivated, and purpose-driven individual. The successful candidate will have a track record of building consumer applications or large internal applications. They must exhibit strong collaboration and communication skills. They should be ready to lead application development in a very dynamic and innovative environment.  

Qualifications:  

• 5+ years of experience in software development, with a strong focus on building applications.  
• Extensive experience with AWS services (including ECS, S3, Lambda, etc) or a similar cloud services provider.  
• Proficient in Python.  
• Demonstrated ability to build scalable, efficient, and secure software applications.  
• Motivated and team oriented, with an ability to thrive in a multidisciplinary environment.  
• Excellent communication and collaboration abilities.  
• Preferred Qualifications:  
• Experience with LLM development.  
• AWS Certifications, such as Solutions Architect Associate or Professional.  
• Able to build applications using the AWS CDK and Typescript.  
• Knowledge of security best practices for SaaS solutions.  

About Flagship  

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  .  

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.  

Privacy Notice for Applicants:  When you apply for a role at Flagship Pioneering or one of its portfolio companies, we collect and use personal information you provide (such as your name, contact details, work history, and application materials) to evaluate your application, communicate with you, and comply with legal obligations. Your application data is processed through Greenhouse, our applicant tracking system, and may also be reviewed using AI-assisted screening tools. We do not sell your personal information. California residents have rights under the CCPA/CPRA including to know, delete, and opt out of the sharing of their personal information. If you are located in the EU or UK, we process your data under GDPR and you have rights to access, rectify, and erase your data. To exercise your rights or for questions, contact View email address on boards.greenhouse.io. 

The salary range for this role is $108,000 - $209,000. Compensation for the role will depend on a number of factors, including a candidate’s qualifications, skills, competencies, and experience. FL105 currently offers healthcare coverage, annual incentive program, retirement benefits and a broad range of other benefits. Compensation and benefits information is based on FL105's good faith estimate as of the date of publication and may be modified in the future.

Privacy Notice for Applicants:  When you apply for a role at Flagship Pioneering or one of its portfolio companies, we collect and use personal information you provide (such as your name, contact details, work history, and application materials) to evaluate your application, communicate with you, and comply with legal obligations. Your application data is processed through Greenhouse, our applicant tracking system, and may also be reviewed using AI-assisted screening tools. We do not sell your personal information. California residents have rights under the CCPA/CPRA including to know, delete, and opt out of the sharing of their personal information. If you are located in the EU or UK, we process your data under GDPR and you have rights to access, rectify, and erase your data. To exercise your rights or for questions, contact View email address on boards.greenhouse.io.