Research Engineer, AI Systems in London

Lightning AI is the company behind PyTorch Lightning. Founded in 2019, we build an end-to-end platform for developing, training, and deploying AI systems—designed to take ideas from research to production with less friction. We serve solo researchers, startups, and large enterprises. Lightning AI operates globally with offices in New York City, San Francisco, Seattle, and London.

The people who thrive here are builders who move fast, communicate openly, take ownership, and continuously improve themselves, their teams, and our company. Here's what that looks like in practice:

• Move with Urgency: We move quickly, make thoughtful decisions, and keep momentum.
• Take Ownership: We own outcomes, not just our individual work.
• Communicate Openly: We communicate directly, seek to understand, and create clarity for others.
• Build Great Teams: We lead by example, empower others, and create healthy teams.
• Raise the Bar: We're always improving ourselves.
• Think Long-Term: We design for what's next.

We're looking for a curious, adaptable Research Engineer who enjoys solving difficult technical problems and building across the AI stack. This role is intentionally broad, with a primary focus on post-training models and the systems that support it. You’ll work across ML engineering, software engineering, and AI systems to improve how we develop, train, evaluate, and deploy models.

What You'll Do:

• Develop and post-train models, while building and improving the systems and workflows needed to run, evaluate, debug, and scale training workloads.
• Build software, tooling, and platform capabilities that improve how researchers, developers, and customers develop, train, and deploy AI systems.
• Contribute to Lightning’s open-source projects by building new features and improving existing functionality.
• Work across deep learning systems, developer tooling, backend services, and platform infrastructure.
• Collaborate directly with customers to understand real-world AI workloads.
• Prototype new ideas, evaluate approaches, and turn successful experiments into production-quality software.
• Partner closely with research, product, and infrastructure engineering teams.
• Debug complex technical problems spanning machine learning, distributed systems, backend software, and developer tooling.
• Learn new technologies quickly and contribute wherever your skills can have the greatest impact.

What You’ll Need:

• Experience building, training, evaluating, or experimenting with deep learning models.
• Hands-on experience with deep learning frameworks such as PyTorch.
• Strong software engineering fundamentals and problem-solving skills.
• Curiosity, initiative, and a demonstrated ability to quickly learn new technologies.
• Excellent communication and collaboration skills.
• Bachelor's degree in Computer Science, Engineering, or a related technical field, or equivalent practical experience.

Ideal Experience:

• Experience with model training at scale.
• Experience with transformer-based language models or modern generative AI systems.
• Experience with distributed systems, cloud infrastructure, or large-scale machine learning workloads.
• Familiarity with technologies such as CUDA, Hugging Face, DeepSpeed, or related AI infrastructure tooling.
• Experience contributing to open-source software or conducting research.
• Startup experience or experience working on highly cross-functional engineering teams.
• Master's degree or higher in Computer Science, Machine Learning, AI, or a related field.

We offer a comprehensive and competitive benefits package designed to support our employees’ health, well-being, and long-term success:

• Comprehensive Health Coverage: Medical, dental, and vision coverage for employees and eligible dependents.
• Meaningful Equity: RSUs that give employees a stake in the company's long-term success.
• Retirement Savings: 401(k) matching (U.S.) and pension contributions (U.K.).
• Flexible Time Off: Unlimited PTO, company holidays, and floating holidays.
• Company-Wide Winter Break: Two weeks of company closure each winter.
• Paid Parental & Family Leave: Paid leave to support you and your family.
• Professional Development: Annual learning and development allowance.
• Wellness Benefits: Wellness and work-from-home stipends.
• Sabbatical Program: Four weeks of paid sabbatical leave after four years of service.
• Flexible Work: Flexible schedules and a hybrid work model.
• In-Office Meals: Complimentary meals at our office hubs.

At Lightning AI, we are committed to fostering an inclusive and diverse workplace. We provide equal employment opportunities to all employees and applicants without regard to any protected characteristic.