Software Engineer

Role: Senior AI Software Engineer to build the agents that sit on top of our search platform: systems that take a user's intent, break it into steps, gather and verify information from the web, and return answers an agent can act on. You will work across applied research and engineering, designing how agents plan, call tools, retrieve, and reason so they accomplish open-ended tasks reliably and at scale. This is a high-ownership role at the intersection of agent systems, retrieval, and product. You will turn frontier-model capabilities into dependable, production-grade agent behavior, and you will own that behavior end to end, from the prompts and tools to the evaluation that proves it works. In this position, your responsibility will be to Design and build AI agents that plan, retrieve, and reason over real-world information to complete open-ended tasks Build the tool interfaces and context engineering that let frontier models use our search and other tools effectively Mine and analyze usage data to build agents that learn and improve continually from how they are used Turn new model capabilities into reliable product features, and own them from prototype to production Define the evaluations, metrics, and guardrails that prove an agent is accurate, grounded, and safe Improve agent quality across reasoning, planning, tool use, and grounding against real user tasks Build the backend and infrastructure that run agents reliably under high volume Collaborate with the search, ML, and product teams to make agent and platform capabilities reinforce each other You may be a good fit if you: 6+ years of software engineering experience, Strong understanding of LLMs and transformer architecture, Able to mine and analyze data to build agents that learn and improve continually, Hands-on experience building agentic systems: tool calling, planning, multi-step or long-running task execution, Experience with agentic frameworks (e.g. LangChain, DeepAgents) and tracing tools (e.g. LangSmith), Strong grasp of context engineering and tool interfaces for frontier LLMs, Comfortable defining the metrics and evaluations that prove a system works, and iterating on them, Strong product judgment; you turn vague needs into reliable systems and ship without waiting for perfect specs, Thrive in a small, fast-moving team and take ownership end to end, Strong candidates may also have experience with: Retrieval-augmented generation, search, or information-retrieval systems, Post-training, reinforcement learning, or fine-tuning for reasoning or tool use, Building developer platforms or reusable primitives (SDKs, tool/plugin systems, workflow engines), Evaluation, benchmarking, or quality systems for LLM-powered products, Time at a fast-growing startup or on a high-ownership engineering team 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, What's it like to work at Nebius: 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, 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.