(Senior) AI/LLM Engineer

Mercura (YC W25) helps the companies that build the real world move at software speed, automating the back-office work that runs the $12 trillion industry behind every hospital, school, and power plant. We started with one of their biggest bottlenecks - turning messy technical requests into accurate quotes - and grew to $2M ARR in our first year. With a team of 16, we're now targeting $10M by the end of 2026 as well as our expansion into the US.About the roleAs an AI/LLM Engineer, you will play a key role in building agentic AI systems end-to-end. This is a fast-paced, hands-on role for engineers with high agency, strong technical depth and founder mindset. You’ll work on building reliable AI systems in production - from retrieval and LLM orchestration to tool-using agents and product integration.If you’re a passionate builder who excels at the intersection of LLMs, data systems, AI, data engineering, and full-stack development, this is your opportunity to shape how users interact with AI in real-world workflows.What you will be working onAgentic Systems: Design and build LLM-powered agentic systems end-to-end, from experimentation to production deploymentRetrieval & Context: Build retrieval and context pipelines (RAG, hybrid search, structured retrieval) to enable reliable reasoning over large volumes of technical and commercial dataAI Evals: Develop evaluation and monitoring systems to measure and improve AI performance in productionData Pipelines: Build scalable pipelines to process and structure large volumes of unstructured documents and dataFeedback Loops: Implement automated feedback pipelines that allow AI systems to learn from usage data and human feedbackAI Infra: Own the architecture and reliability of AI systems in production, ensuring they are fast, scalable, and robustProduct Integration: Collaborate with other stellar engineers to deeply integrate AI capabilities into the product experienceWhat we offerSteepest possible learning curve: There's no faster way to grow than building a company from scratch. You'll be thrown into the cold water, do things no one has done before, and have founder-like freedom in your domain. Over five Mercura alumni have gone on to found their own companies and raise millions after their time with us.Build something with real-world impact: We ship code that directly helps a massive, yet overlooked manual industry run more efficiently and sustainably. With us, you can work on AI that contributes to economic growth and stability on a huge scale.Ownership over comfort: You own a real area end to end. No one stands between you and your problem. It's uncomfortable at times, and that's exactly why you'll grow faster here than in any normal job.Exceptional colleagues: You'll work alongside experienced operators, ex-founders, Science Olympiad medallists, and top graduates from Google, Bain, MIT, TUM, Harvard, CDTM, Oxford, and Cambridge. The bar stays high because the people next to you are the biggest lever for your growth.Radical clarity: You'll always know where the company stands and why we decide what we decide — the real numbers, the wins and the setbacks, and the thinking behind them. Your input is genuinely wanted, and the best argument wins.Tools, no questions: Your own company card and any AI or productivity tools you need to do your best work, without approval theater.Real shares: Real equity in Mercura with the most favorable tax treatment. No VSOP, no ESOP.The everyday: Free team dinners up to 4x/week, UrbanSportsClub membership, a company bike, and team workouts 3x/week. Easy relocation to Munich — our office sits in the WERK1 startup incubator, with an apartment next door for around €800/month.What we're looking forTechnical Skills & Experience:Proven track record of architecting and building complex, AI/LLM-powered systems or agents in production, including model serving, orchestration of agent workflows, monitoring, and scaling AI workloadsDesigning systems that process and structure large volumes of unstructured dataDeveloping evaluation and feedback loops to measure and improve AI system performanceExperience with Python is requiredExperience in full-stack development (React / Typescript / FastAPI) is a plusMindset & Commitment:High agency & ownership: You develop new ideas and drive them in execution under minimal guidanceMission-driven: Your job is part of how you define yourself. You are fully committed to your work and achieving ambitious goals amid uncertainty.Product mindset: You demonstrate product thinking on a deep level and solve problems end-to-endYou’re excited to iterate quickly and build software in a fast-paced startup environmentYou want to work in-person in Munich with a higher intensity than in a 9-5 jobYour team & mentors You will work withSean (Co-Founder & CTO; Silver Medallist at the International Physics Olympiad (IPhO))Kolya (prev. SWE at SF-based startup Etleap)Gabriel (built Maastricht University's course selection system; Oxford graduate)Admir (Bronze Medallist at the International Olympiad in Informatics (IOI))Nico (prev. Engineering at SaaS startups Luminovo & Fides)Your mentors will beRohan Ramanath (General Manager AI Product at Nubank, prev. co-founder Hyperplane) Daniel Ribeiro Silva (Senior Director of ML at Nubank, prev. co-founder Hyperplane)Why MercuraJoin an ambitious and caring team: Your future colleagues are experienced operators, ex-founders, Science Olympiad medallists, and top graduates from places such as Google, Bain, MIT, TUM, Harvard, CDTM, and Cambridge. We bring extraordinary people together and deeply invest in your growth as your mentors, teammates and friends. We care, trust, and support one another, and we make sure that fun is at the heart of everything we do.Work with the latest tech: AI is at the core of our product, and use the latest tech across our product and processes to tackle meaningful challenges and shape how users interact with AI.Thrive in a high-growth, high-commitment environment: We’re growing extremely fast because we always put our work and our customers first. If you excel in fast-paced settings and want to grow as part of something big from day one, Mercura is for you.Build something with real-world impact: We ship code that directly helps a massive, yet overlooked manual industry run more efficiently and sustainably. With us, you can work on AI that contributes to economic growth and stability on a huge scale.Build a company: As an early team member, you will have a direct, lasting impact on our culture, processes, technology, and product. Joining us offers immense rewards: ownership, financial upside, and hands-on experience building a company from the ground up. Our track record speaks for itself - over five Mercura alumni have gone on to found their own companies and raise millions after their time with us.About the interviewIntro Call – Casual chat with one of our founders to get to know each other and learn about Mercura.Technical Take-Home – A 3-hour exercise based on a real problem from our workTechnical Interview – Present your results in a 45-minute session and discuss your approach.On-Site – Get to know the team at our Munich office.Offer – If we see a great fit, we'll make you an offer. Once you accept, we'll do 2–3 reference checks. About the FoundersWe are Lukas, Stefan & Sean, the co-founders of Mercura. We share a deep commitment to excellence and the discipline to pursue what others might consider impossible. Two of us come from non-academic families, and we all know what it means to create our own paths and overcome barriers. This experience shapes our belief in equal opportunity and fuels our dedication to social mobility.Lukas (left) is responsible for business development at Mercura. With his background as a Data Scientist at Allianz and at Google in Silicon Valley, he brings extensive expertise in data and AI. Lukas’ family has been active in the construction industry for over 100 years, giving him a deep understanding and passion for the sector's specific needs.Sean (middle) is responsible for technical development at Mercura. As a top 0.01% physicist, Sean earned a Silver medal for Germany at the International Physics Olympiad (IPhO), began researching with the Max Planck Institute at the age of 16, and has since published at leading machine learning conferences. Stefan (right) leads product development at Mercura. Previously, he worked in management consulting at Bain & Company, where he helped manufacturers improve their operations. Stefan leverages his research experience at the Massachusetts Institute of Technology (MIT) and Harvard Business School to develop innovative solutions for the industry.At Mercura, we believe that the best ideas emerge when people from different backgrounds collaborate together. We hire based on ability, mindset, and values, and we live by one simple rule: the best idea wins.Beyond Mercura, we actively support initiatives that promote diversity and gender equity and commit a portion of our personal income each year to organizations expanding opportunity for others. Our company valuesCustomer first. We stay close to our customer’s reality and use their feedback to build what truly matters and earn their lasting trust.Ownership. We take responsibility end-to-end and act proactively to pursue the most ambitious goals.Enjoy the ride. We build a culture where people can be themselves, have fun doing meaningful work, and celebrate wins along the way.Let the best ideas win. We challenge each other respectfully and judge ideas by merit, not who said it.Down-to-earth. We are approachable, humble, and hands-on, bringing both heart and mind to everything we do.