Senior ML Engineer (AI Research/ Portability)

Nebius is leading a new era in cloud infrastructure for the global AI economy. We are building a full-stack AI cloud platform that supports developers and enterprises from data and model training through to production deployment, without the cost and complexity of building large in-house AI/ML infrastructure.

Built by engineers, for engineers. From large-scale GPU orchestration to inference optimization, we own the hard problems across compute, storage, networking and applied AI.

Listed on Nasdaq (NBIS) and headquartered in Amsterdam, we have a global footprint with R&D hubs across Europe, the UK, North America and Israel. Our team of 1,500+ includes hundreds of engineers with deep expertise across hardware, software and AI R&D.

This role is for Nebius AI R&D, a team focused on applied research in AI. Our Portability research aims to make intelligent agent systems work reliably as models, providers, harnesses, skills, memory systems, and deployment environments change. We build and evaluate portable layers that preserve capability, context, identity, provenance, and user control across heterogeneous systems. Research areas include:

• Per-turn model routing across quality, cost, latency, capability, cache state, and reliability objectives

• Provider and protocol portability across frontier models, open-source models, local inference, and compatible APIs

• Agent and harness interoperability, including transferable skills, capability profiles, actions, tools, and trajectories

• Portable, user-owned memory and context with scoped identity, provenance, retrieval, feedback, and reviewable compaction

• Agent interchange standards, conformance testing, tool and MCP access, and agent-to-agent communication

• Agent and harness optimization through evaluation, distillation, customization, and multi-agent learning

You will design and build research prototypes and robust systems at the seams between models, providers, and agent runtimes. You will formulate research questions, develop evaluation methods, test ideas in realistic agent workflows, and turn promising results into reusable components. The work will often involve collaboration with adjacent research, infrastructure, security, product, and engineering teams, where findings are validated and applied in practice.

We are currently looking for senior- and staff-level ML engineers to work on