Technical Staff, Data - London

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.

• Conduct cutting-edge research in:

  • Reinforcement learning for reasoning and planning (long-horizon, hierarchical control)

  • Agentic capabilities and generalization

• Lead Data and RL environment initiatives:

  • Curate dataset mixtures and design learning curricula (exploration, rewards, scaling laws)

  • Implement ML data pipelines for large-scale RL training

  • Scrape, collect and curate training and evaluation data

  • Build and maintain custom RL environments and evaluation benchmarks

• Collaborate with a world-class research team to publish and open-source impactful work

• Keep up with the latest advancements in agentic and LLM-based research, and bring relevant ideas into our systems

• Strong background in LLMs and/or reinforcement learning

• Demonstrated ability to carry out end-to-end ML research (problem formulation, experimentation, analysis)

• Experience training large-scale models or working with distributed training infrastructure

• A publication record in top ML conferences (NeurIPS, ICML, ICLR, etc.) is a strong plus

• Familiarity with RL environments is a plus

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, wellness and time-saver stipend, commute benefits, education stipend, and relocation support.

• Opportunities to connect with teammates: lunch and dinner are provided daily. We have regular off-sites and team celebrations.