AI Research Engineer in London

About HASH

At HASH, we're building infrastructure to solve information failure and help everybody make the right decisions. Our open-source platform helps firms integrate both structured and unstructured information into knowledge graphs that support simulating, optimizing and automating processes. We’re building toward world models from a radically different perspective to most industry labs. If you want to work on ambitious, original research with the chance to influence both scientific direction and the company itself, we’d love to hear from you.

About the role

In the last 6 months we've seen significant growth and are now scaling fast. We're hiring exceptional AI researchers in London and Berlin to shape the next generation of foundation models in Europe, both developing new AI models and architectures in-house and post-training existing open-source base models. This is not a role focused only on applying existing models. You’ll work on both:

• developing new model architectures in-house in support of deterministic simulation, and
• post-training and adapting state-of-the-art open-source base models.

Requirements

• Strong research track record in machine learning, deep learning, or foundation models: evidenced by research publications, open-source contributions, or other evidence of original technical work.
• Deep understanding of modern model architectures, training dynamics, inference optimization, scaling, and evaluation: transformer, diffusion, and exotic model architectures, sequence modeling, multimodal learning, and generative modeling.
• Hands-on experience training, fine-tuning, or post-training large models: in particular preference optimization, synthetic data, distillation, continual learning, or alignment.
• Strong coding and experimental skills: ideally in Python (and/or Rust) and modern ML tooling.
• Ability to move fluidly between research ideas and practical implementation: comfort quickly moving from concept to early-proof right through to release and productization.
• High agency, strong taste, and excitement about building something category-defining from Europe: we're looking for researchers who are all-in.

What you'll work on

• Research and develop novel model architectures for reasoning, representation learning, and world modeling.
• Post-train and adapt open-source foundation models for high-performance real-world use cases.
• Design, run, and analyze experiments across training, evaluation, and scaling.
• Work across data, systems, and product to turn research into deployed capability.
• Contribute to research direction, technical strategy, and long-term model roadmap.
• Help define the culture and standards of a high-talent, research-driven founding team.

Why HASH

• Work on first-principles AI research tied to a large and important real-world mission.
• Join at a moment of rapid growth, with outsized scope and influence.
• Help build a leading frontier AI lab in Europe with global ambition.
• Work alongside founders who have previously built and exited businesses worth billions of dollars.
• Be part of a team that moves fast, is enthusiastically open source, and is in it for the long-term.

Benefits

Our team have founded and sold billion-euro companies from scratch. We offer leading equity-weighted total compensation, including competitive salaries and tax-advantaged options. We meet together quarterly in-person for whole-team retreats, provide engineers with generous learning and tech budgets, and recognise and reward output. This role pays £130,000-£220,000 base/bonus + meaningful equity.