Staff / Principal Machine Learning Engineer, Serving - UK

About the Position

Staff / Principal Machine Learning Engineer, Serving - UK

Inworld is a research lab of top researchers and engineers, building the world’s top-ranked realtime voice models. Today, our models are the #1 ranked realtime voice models in the world, powering the largest consumer-facing AI applications across various categories. Our work spans research and development, optimizing realtime inference, and creating best-in-class APIs and products.

Responsibilities

• Design and develop scalable backend services
• Write clean, maintainable code
• Collaborate with frontend team

Requirements

• Inference Optimization: Deep understanding of modern serving frameworks and techniques like vLLM or TRT-LLM.
• Model Acceleration: Hands-on experience with quantization, distillation, caching strategies, continuous batching, paged attention, and speculative decoding.
• High-Performance Systems: Proficiency in C++, CUDA, Rust, or highly optimized Python. You know how to profile code and squeeze every ounce of performance out of NVIDIA GPUs.
• Distributed Systems & Scaling: Experience with Kubernetes, Ray, custom load balancing, multi-GPU/multi-node inference, and reliably handling thousands of concurrent connections.
• Public work: Non-trivial systems programming projects, open-source contributions to major inference engines, or deep-dive technical write-ups.
• Full-cycle ownership: You can take a model from the research team, containerize it, optimize its serving, and ensure it runs reliably in production.
• Background: PhD in CS, Physics, Math, or equivalent practical experience building backend or ML systems.

We Offer

• Competitive salary range: £140,000 – £200,000
• Equity and benefits
• Flat structure, fast iterations, minimal process theater

About the Company

Inworld is a research lab of top researchers and engineers, building the world’s top-ranked realtime voice models. We’ve raised more than $125M from Lightspeed, Section 32, Kleiner Perkins, Microsoft’s M12 venture fund, Founders Fund, Meta, and Stanford, among others. Our technology has powered experiences from companies such as NVIDIA, Microsoft Xbox, Niantic, Logitech Streamlabs, Wishroll, Little Umbrella, and Bible Chat. We’ve also been recognized by CB Insights as one of the 100 most promising AI companies globally and have been named one of LinkedIn’s Top 10 Startups in the USA.