Member of Technical Staff - Post-Training

Reflection AI; Greater London; On-site; GBP 75,000 - 110,000; Full time

Benefits offered by this job

Top-tier compensation

Comprehensive medical, dental, vision, life, and disability insurance

Fully paid parental leave

Paid time off

Paid lunches and team celebrations

Meals provided

Job summary

A cutting-edge AI company in Greater London is seeking an Entry-Level Member of Technical Staff - Post-Training. The role involves building systems that enhance pre-trained models and driving innovative research initiatives in machine learning. Candidates should have a strong understanding of ML fundamentals, excellent engineering skills, and a passion for collaborative improvement. The company offers top-tier compensation, comprehensive health benefits, paid parental leave, and opportunities for team engagement, ensuring impactful work and support for employees.

Qualifications

• Deep understanding of machine learning fundamentals and practical experience with large-scale LLM training.
• Strong engineering skills to engage with complex ML codebases.
• Experience in improving model behavior through data or reinforcement learning techniques.
• Evidence of owning ambitious research or engineering agendas with measurable model gains.
• Thrive in a fast-paced, high-agency startup environment; bias toward action and clarity of execution.
• Able to work fluidly across research and infra boundaries.
• Strong communication capabilities and comfort working collaboratively.
• Passionate about advancing the frontier of intelligence.

Responsibilities

• Build systems that transform powerful pre-trained models into aligned and general agents.
• Drive research and engineering initiatives focused on post-training improvements.
• Collaborate across teams to enhance model capabilities.
• Collaborate across pre-training and post-training teams to deliver step-function gains in model capability.
• Contribute to shaping our understanding of how large models learn to reason, follow instructions, and improve through reinforcement learning.

Skills

Machine learning fundamentals

Large-scale LLM training

Strong engineering skills

Collaborative communication

Research agenda

Communication

Cross-functional

Job description

Member of Technical Staff - Post-Training

Join to apply for the Member of Technical Staff - Post-Training role at Reflection AI

Our Mission Reflection’s mission is to build open superintelligence and make it accessible to all. We’re developing open weight models for individuals, agents, enterprises, and even nation states. Our team of AI researchers and company builders come from DeepMind, OpenAI, Google Brain, Meta, Character.AI, Anthropic and beyond.

About The Role

• Build systems that transform powerful pre-trained models into aligned and general agents.
• Drive research and engineering initiatives that push the frontier of post-training, from data curation to large-scale optimization.
• Develop data generation pipelines, reward models, reinforcement learning algorithms, and inference-time scaling techniques.
• Collaborate across pre-training and post-training teams to deliver step-function gains in model capability.
• Contribute to shaping our understanding of how large models learn to reason, follow instructions, and improve through reinforcement learning.

About You

• Deep understanding of machine learning fundamentals and practical experience with large-scale LLM training.
• Strong engineering skills, comfortable diving into complex ML codebases and distributed systems.
• Experience improving model behavior through data, reward modeling, or RL techniques.
• Evidence of owning ambitious research or engineering agendas that led to measurable model improvements.
• Thrive in a fast-paced, high-agency startup environment; bias toward action and clarity of execution.
• Able to work fluidly across research and infra boundaries.
• Strong communication capabilities and comfort working collaboratively.
• Passionate about advancing the frontier of intelligence.

What We Offer

We believe that to build superintelligence that is truly open, you need to start at the foundation. Joining Reflection means building from the ground up as part of a small talent-dense team. You will help define our future as a company, and help define the frontier of open foundational models. We want you to do the most impactful work of your career with the confidence that you and the people you care about most are supported.

• Top-tier compensation: Salary and equity structured to recognize and retain the best talent globally.
• Health & wellness: Comprehensive medical, dental, vision, life, and disability insurance.
• Life & family: Fully paid parental leave for all new parents, including adoptive and surrogate journeys. Financial support for family planning.
• Benefits & balance: paid time off when you need it, relocation support, and more perks that optimize your time.
• Opportunities to connect with teammates: lunch and dinner are provided daily. We have regular off-sites and team celebrations.

Seniority level

• Entry level

Employment type

• Full-time

Job function

• Engineering and Information Technology

Industries

• Software Development