Senior AI Engineer – Agentic Systems & LLM Applications

Job description

**This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior AI Engineer – Agentic Systems & LLM Applications based in Spain.** This role sits at the intersection of product engineering and frontier AI, focused on building the next generation of AI-native applications. You will design and scale autonomous agents capable of reasoning, taking actions, and solving complex, non-deterministic workflows in production. The position combines LLM application development, agent orchestration, advanced retrieval, developer tooling, and production AI engineering. You will work with leading foundation models and modern AI infrastructure to create reliable, observable, and low-latency systems. A major focus will be moving AI solutions beyond prototypes by implementing rigorous evaluation, monitoring, and optimization practices. As part of a distributed, global-first team, you will have significant ownership over technical architecture and product direction. This is an opportunity to work on challenging AI problems while turning emerging capabilities into practical products with tangible user impact. ### Accountabilities: - Design and implement autonomous agents and multi-agent orchestration systems capable of handling complex, open-ended tasks. - Build and optimize production-grade applications on top of leading foundation models, with a focus on reliability, observability, scalability, and low-latency performance. - Architect advanced Retrieval-Augmented Generation (RAG) pipelines and vector database strategies that provide agents with accurate, relevant, and real-time context. - Develop sophisticated tool-calling, planning, reasoning, and autonomous execution workflows for AI agents. - Contribute to AI-powered developer tools and internal frameworks that accelerate the development and deployment of AI-native products. - Establish rigorous evaluation frameworks and Evals to measure model and agent performance in production environments. - Implement monitoring, fine-tuning, testing, and optimization pipelines to improve accuracy, reliability, and safety. - Collaborate across product and engineering functions to integrate foundation models into solutions that address real-world user needs. - Help shape the technical architecture and engineering practices for scalable AI-native systems. - Continuously evaluate emerging AI technologies, frameworks, and approaches and identify opportunities to incorporate them into production systems. **Requirements:** - Proven experience building production applications using large language models, AI agents, or other advanced AI technologies, ideally within an AI-native startup, research environment, or developer-tool organization. - Deep understanding of agentic systems, including agent frameworks, tool calling/function calling, autonomous planning, and reasoning loops. - Expert-level proficiency in Python and/or TypeScript with Node.js. - Hands-on experience with LangChain, LlamaIndex, or custom-built AI orchestration frameworks. - Strong expertise with vector databases such as Pinecone, Weaviate, or Milvus. - Experience designing efficient machine learning and data pipelines. - Strong understanding of foundation model applications and the practical challenges of deploying LLM-powered systems at scale. - Experience building sophisticated RAG architectures and retrieval strategies. - Strong product intuition and the ability to translate emerging AI capabilities into useful, reliable products rather than purely academic experiments. - Experience with production AI engineering practices, including evaluation, monitoring, optimization, and reliability. - Ability to work effectively in a distributed, global-first environment with a high degree of autonomy and ownership. - Strong problem-solving skills and a willingness to work on complex, ambiguous technical challenges. **Benefits:** - Fully remote opportunity with a global-first distributed team. - Primary hiring regions include the United States, Europe, and India. - Opportunity to work directly on autonomous agents, LLM applications, advanced RAG, and AI-native product infrastructure. - Exposure to leading foundation models and modern AI development frameworks. - Significant technical ownership at the intersection of product engineering and frontier AI research. - Opportunity to build production-grade AI systems rather than experimental prototypes. - For US-based candidates, a 3-month contractor-to-hire period followed by potential conversion to full-time employment. - For candidates outside the US, long-term independent contractor engagement through OnTop. - Opportunity to contribute to AI-powered developer tools and emerging AI technologies. - Potential for significant career growth in a rapidly evolving AI environment.