Specialised AI Engineer in London

About Nscale

Nscale is taking on the hyperscalers by building a vertically integrated GenAI cloud platform. We own the data centres, software, and applications that power today's AI stack using sustainable technology solutions. We thrive on a culture of relentless innovation, ownership, and accountability, where every team member takes pride in their work and drives it with excellence and urgency. As a Nscaler, you’ll build trust through openness and transparency, where everyone is inspired to do their best work. Collaboration is key, and we work together swiftly and respectfully, embracing adaptability and resilience in all we do.

About the Role

Nscale is looking for Senior / Staff AI Engineers to join our core AI team and build the systems that power our GenAI cloud platform. This role sits at the heart of our AI services platform, designing and optimising distributed systems that power large-scale training, post-training, evaluation, and low-latency, high-throughput inference under strict performance and efficiency constraints. You may specialise deeply in areas such as inference optimisation, large-scale training, post-training (fine-tuning, alignment), or evaluation systems, or operate across multiple parts of the stack. In all cases, you’ll work on hard systems problems at scale, where performance, efficiency, and developer experience are critical. This is a hands-on role for engineers who want to push the boundaries of how AI systems are built, optimised, and consumed by other AI engineers.

Responsibilities

• Design, build, and optimise scalable AI platform systems spanning (one or more):

• Drive inference performance and efficiency, including:

• KV cache management, continuous batching, speculative decoding
• Quantisation (INT8/4, FP8), sparsity, pruning, and model compression

• Fine-tuning (LoRA, QLoRA, adapters, full fine-tuning)
• Alignment (RLHF, DPO, reward modelling)
• Agentic RL (tool calling, off-policy training, parallel thinking, decoupled sampling and updating)
• Dataset curation and data processing workflows

• Model quality, safety, and regression
• System performance (latency, throughput, cost)
• Real-world behaviour and feedback loops

Requirements

• 5+ years of experience building production systems in machine learning, distributed systems, or high-performance infrastructure
• 4+ years of hands-on experience in at least one core area, within large-scale, production AI environments (e.g., AI labs, hyperscalers), such as:

• Inference optimisation
• Large-scale training / pre-training systems
• Post-training (fine-tuning, alignment, distillation)
• Evaluation and benchmarking frameworks

• GPU/accelerator optimisation (CUDA, ROCm, or similar)
• Memory management and system-level performance tuning

Preferred

• Experience developing large-scale and high-load production systems.
• Experience working in containerised, distributed environments (e.g., Kubernetes, large-scale clusters)
• Experience contributing to or working with widely used/open-source AI frameworks or systems is strongly preferred
• Hands-on experience with advanced inference optimisation techniques, such as KVCache, MoE, adaptive batching, or gradient checkpointing.
• Experience developing APIs using OpenAPI 3.0+ specifications.
• Knowledge of efficient training and inference evaluation strategies, with demonstrated success in improving model efficiency.

At Nscale, we are committed to fostering an inclusive, diverse, and equitable workplace. We believe that a variety of perspectives enriches our work environment, and we encourage applications from candidates of all backgrounds, experiences, and abilities. We strongly encourage applications from people of colour, the LGBTQ+ community, people with disabilities, neurodivergent people, parents, carers, and people from lower socio-economic backgrounds. If there’s anything we can do to accommodate your specific situation, please let us know.

The responsibilities outlined in this job description are not exhaustive and are intended to provide a general overview of the position. The employee may be required to perform additional duties, tasks, and responsibilities as assigned by management, consistent with the skills and qualifications required for the role.