Staff / Senior Software Engineer (Agentic Search) - Runtime in London

About Nebius

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 optimisation, 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.

The Product

In a rapidly evolving world, trust in AI depends on AI agents being grounded in fresh, verified real‑world data. Search is the foundation that makes this possible. We are building an agent‑native search platform designed specifically for AI systems rather than human users. Our product provides programmatic, low‑latency, and observable search APIs that AI agents use to retrieve, filter, and reason over real‑world information at scale.

The Role

We are looking for a Senior Software Engineer to work on the runtime systems of a novel search engine tailored for agentic AI consumption. In this role, you will focus on building low‑latency, high‑throughput systems that serve search queries in real time. You will work on the critical path of user‑facing requests, where performance, predictability, and efficiency directly impact product quality. You will design and operate systems that handle thousands of requests per second under strict latency budgets, optimising every layer from request handling to data access and response assembly.

Responsibilities

• Design, implement, and operate core runtime services for serving search queries at scale
• Build and optimise request flows, including query processing, retrieval orchestration, and response assembly under strict latency budgets
• Develop systems that maintain performance and predictability under high load
• Optimise CPU, memory, and data access patterns in performance‑critical paths
• Ensure reliability, observability, and predictability across production services
• Build well‑tested systems with clear responsibilities and interaction contracts, while remaining flexible as architecture evolves
• Define and implement observability primitives, including structured logs, metrics, traces, and latency breakdowns
• Monitor throughput, latency, and resource usage, and drive improvements in performance and cost efficiency
• Collaborate with indexing and ML teams to integrate retrieval and ranking components, keeping ML logic decoupled from core system internals
• Support experimentation and iteration through controlled rollouts and rigorous benchmarking

Qualifications

• Have 5+ years of experience as a software engineer working on production backend systems
• Have strong hands‑on expertise in C++ or Rust in real‑world, high‑load services
• Have built and operated high‑load, low‑latency user‑facing systems handling thousands of RPS under strict latency constraints
• Understand performance at a systems level — CPU, memory, networking, and data access
• Have operated your own code in production: deployed it, debugged incidents, and rolled back changes when necessary
• Think end‑to‑end about request flows rather than staying within isolated components
• Can balance correctness, latency, and development velocity, making pragmatic tradeoffs when scope or time requires
• Collaborate effectively across engineering, ML, and product teams, communicating clearly in cross‑functional settings

Strong Candidates May Also Have Experience With

• DBMS internals (open source or SaaS) and cloud infrastructure
• High‑load web applications or large‑scale APIs
• Performance‑critical systems such as trading platforms or real‑time data pipelines
• Low‑level performance tuning and hardware‑level optimisation
• Open‑source contributions or active involvement in the engineering community
• Competitive programming or CTF participation
• SHAD or similar advanced technical programmes
• Conference talks or technical publications

Benefits & Perks

• Competitive compensation
• Career growth and learning opportunities
• Flexibility and ownership
• Collaborative and innovative culture
• Opportunity to work on impactful AI projects
• International environment and talented teams
• Fast moving - Bold thinking - Constant growth - Meaningful impact - Trust and real ownership - Opportunity to shape the future of AI

Equal Opportunity Statement

Nebius is an equal opportunity employer. We are committed to fostering an inclusive and diverse workplace and to providing equal employment opportunities in all aspects of employment. We do not discriminate on the basis of race, color, religion, sex (including pregnancy), national origin, ancestry, age, disability, genetic information, marital status, veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by applicable law. Applicants must be authorized to work in the country in which they apply and will be required to provide proof of employment eligibility as a condition of hire. If you need accommodations during the application process, please let us know.