Machine Learning Research Engineer

Socket.dev; Cambridge (MA); On-site; USD 120,000 - 192,500; Full time

Job summary

FL105 seeks a Machine Learning Research Engineer to innovate, develop, and apply ML methods for foundational psychological tools. The role emphasizes reinforcement learning from human feedback, supervised fine tuning, and scalable ML pipelines in a fast-moving startup environment.

You will collaborate with world-class scientists and engineers to push the state of the art in AI-driven wellbeing applications and context engineering, leveraging LLMs and open-ended research challenges.

Qualifications

• Masters level in CS, ML preferred; can be relaxed for exceptional candidates.
• Strong foundation in machine learning, deep learning, and NLP.
• Publications at top ML/NLP venues are a bonus.
• Experience deploying LLM-powered applications in production environments (PyTorch, vLLM, LangGraph).
• Proficiency in Python and ML data pipelines.
• Self-motivated with ability to work in ambiguous, fast-moving environments.
• Excellent communication and presentation skills.

Responsibilities

• Design, develop, and deploy ML-powered applications using LLMs for wellbeing challenges.
• Collaborate with psychological experts to translate interdisciplinary insights into computational frameworks.
• Advance context engineering, agentic AI, and learning from human feedback.
• Build scalable data collection, labeling, training, and deployment pipelines for LLM-based systems.
• Support integration of ML systems into real-world applications with measurable outcomes.
• Communicate findings to a multi-disciplinary audience.

Skills

ML fundamentals

NLP

Python

PyTorch

LLM deployment

RLHF

Research communication

Independent work

Education

Master's degree in CS/ML

Tools

PyTorch

vLLM

LangGraph

Job description

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

FL105 seeks a talented Machine Learning Research Engineer. The successful candidate will innovate, develop and apply machine learning (ML) methods to create foundational psychological tools. This position is ideal for someone with broad expertise in machine learning, reinforcement learning from human feedback, supervised fine tuning, and computational sciences who is looking to join a very dynamic and innovative environment and pioneer the next frontier of innovation, application, and human-ai interactions enabled by state-of-the-art models. A successful candidate should have a passion for building technologies that enable others to maximize their potential.

Working at FL105, you will have the opportunity to work with world-class scientists, engineers, and researchers who work on cutting-edge ai research and applications.

Key Responsibilities

• Design, develop, and deploy ML-powered applications that leverage large language models (LLMs) to address complex challenges in wellbeing.


• Collaborate with psychological experts and translate interdisciplinary insights into computational frameworks.


• Help advance the state of the art in context engineering, agentic AI and learning from human feedback.


• Build scalable pipelines for data collection, labeling, training, and deployment of LLM-based systems.


• Support the integration of ML systems into real-world applications with measurable outcomes.


• Communicate findings to a multi-disciplinary audience.

Professional Experience & Qualifications

• Masters level (or above) experience in CS, ML, and AI is preferred, but can be relaxed for exceptional candidates.


• Strong foundation in machine learning, deep learning, and natural language processing (NLP).


• Publications at top ML / NLP venues such as NeurIPS, ICML, ACL and EMNLP are a bonus


• Proven experience deploying LLM-powered applications in production environments, including expertise in frameworks like PyTorch, vLLM, and LangGraph.


• Proficiency in Python and tools for ML development, large-scale data pipelines and pre-processing, and standard evaluation protocols.


• Self-motivated and comfortable working in ambiguous, fast-moving environments with evolving goals.


• Excellent communication and presentation skills.


• Must be able to think independently and work collaboratively.


• Experience in a previous startup is a plus.

About Flagship Pioneering

Flagship Pioneering invents and builds platform companies, each with the potential for multiple products that transform human health, sustainability and beyond. Since its launch in 2000, Flagship has originated more than 100 companies. Many of these companies 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.

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

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.

We recognize that great candidates often bring unique strengths without fulfilling every qualification. If you have some of the experience listed above but not all, please apply anyway. We are dedicated to building diverse and inclusive teams and look forward to learning more about your background and interest in Flagship.

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 [e-mail].

The salary range for this role is $120,000 - $192,500. 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 [e-mail].