Senior Machine Learning Systems Engineer (Frameworks & Tooling) in London

Requirements

• Strong engineering experience in large-scale distributed training or HPC systems
• Deep familiarity with JAX internals, distributed training libraries, or custom kernels/fused ops
• Experience with multi-node cluster orchestration (Slurm, Ray, Kubernetes, or similar)
• Comfort debugging performance issues across CUDA/NCCL, networking, IO, and data pipelines
• Experience working with containerized environments (Docker, Singularity/Apptainer)
• A track record of building tools that increase developer velocity for ML teams
• Excellent judgment around trade-offs: performance vs complexity, research velocity vs maintainability
• Strong collaboration skills — you’ll work closely with infra, research, and deployment teams
• (Desirable) Experience with training LLMs or other large transformer architectures
• (Desirable) Contributions to ML frameworks (PyTorch, JAX, DeepSpeed, Megatron, xFormers, etc.)
• (Desirable) Familiarity with evaluation and serving frameworks (vLLM, TensorRT-LLM, custom KV caches)
• (Desirable) Experience with data pipeline optimization, sharded datasets, or caching strategies
• (Desirable) Background in performance engineering, profiling, or low-level systems
• (Desirable) Bonus: paper at top-tier venues (such as NeurIPS, ICML, ICLR, AIStats, MLSys, JMLR, AAAI, Nature, COLING, ACL, EMNLP)

If some of the above doesn’t line up perfectly with your experience, we still encourage you to apply!

What the job involves

• We’re looking for a senior engineer to help build, maintain and evolve the training framework that powers our frontier-scale language models.
• This role sits at the intersection of large-scale training, distributed systems, and HPC infrastructure.
• You will design and maintain the core components that enable fast, reliable, and scalable model training — and build the tooling that connects research ideas to thousands of GPUs.
• If you enjoy working across the full stack of ML systems, this role gives you the opportunity and autonomy to have massive impact.
• Build and own the training framework responsible for large-scale LLM training.
• Design distributed training abstractions (data/tensor/pipeline parallelism, FSDP/ZeRO strategies, memory management, checkpointing).
• Improve training throughput and stability on multi-node clusters (e.g., GB200/300, AMD, H200/100).
• Develop and maintain tooling for monitoring, logging, debugging, and developer ergonomics.
• Collaborate closely with infra teams to ensure our cluster, container environments, and hardware configurations support high-performance training.
• Investigate and resolve performance bottlenecks across the ML systems stack.
• Build robust systems that ensure reproducible, debuggable, large-scale runs.
• You’ll work on some of the most challenging and consequential ML systems problems today.
• You’ll collaborate with a world-class team working fast and at scale.
• You’ll have end-to-end ownership over critical components of the training stack.
• You’ll shape the next generation of infrastructure for frontier-scale models.
• You’ll build tools and systems that directly accelerate research and model quality.

Sample Projects:

• Build a high-performance data loading and caching pipeline.
• Implement performance profiling across the ML systems stack.
• Develop internal metrics and monitoring for training runs.
• Build reproducibility and regression testing infrastructure.
• Develop a performant fault-tolerant distributed checkpointing system.