AI/LLM Engineer

About Mercura

Mercura is building AI software for the backbone of our economy.

Backed by Y Combinator, we raised a heavily oversubscribed round at one of the highest valuations in our cohort. As one of Europe's fastest growing startups, we surpassed $2M in ARR in in our first year. Now, we are looking for team members ready to go all-in to help us reach our next milestone: $10M ARR by the end of 2026.

One of our co-founders, Lukas, grew up in a trades family that has been active in the construction industry for over 115 years. Having worked on the construction site himself, he learned first-hand how slow and manual quoting still is in the industry.

In an era where AI becomes ubiquitous, we set out on a deeply personal mission: bring AI to the backbone of our economy - to the companies that keep our world running. To amplify human expertise and free people to do what only humans can do.

About the role

As 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 on

• Agentic Systems: Design and build LLM-powered agentic systems end-to-end, from experimentation to production deployment

• Retrieval & Context: Build retrieval and context pipelines (RAG, hybrid search, structured retrieval) to enable reliable reasoning over large volumes of technical and commercial data

• AI Evals: Develop evaluation and monitoring systems to measure and improve AI performance in production

• Data Pipelines: Build scalable pipelines to process and structure large volumes of unstructured documents and data

• Feedback Loops: Implement automated feedback pipelines that allow AI systems to learn from usage data and human feedback

• AI Infra: Own the architecture and reliability of AI systems in production, ensuring they are fast, scalable, and robust

• Product Integration: Collaborate with other stellar engineers to deeply integrate AI capabilities into the product experience

What we offer

• Learn to build a company: Over five Mercura alumni have gone on to found their own companies and raise millions after their time with us. At Mercura, you’ll take on real responsibility and gain the hands-on experience only possible in a high-growth startup.

• Guaranteed career advancement opportunities in a rapidly growing team

• An ambitious team that feels like family and sees their work as more than just a job

• Real shares in our company with the most favorable tax treatment - no VSOP/ESOP

• Free team dinner (up to 4x/week)

• UrbanSportsClub membership and access to a company bike - join our team workouts 3x/week

• Easy relocation to Munich - our office is located in the Werk1 Startup Incubator, where you can rent a 1-bedroom apartment right next to the office for just €800/month

• Access to any AI or productivity tools you need

The target total compensation (cash+bonus+equity) for this position is €85,000-€180,000 annually. Actual offers and compensation are based on specific job duties, experience, performance, total rewards structure, and other considerations.

What we're looking for

Technical 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 workloads

• Designing systems that process and structure large volumes of unstructured data

• Developing evaluation and feedback loops to measure and improve AI system performance

• Experience with Python is required

• Experience in full-stack development (React / Typescript / FastAPI) is a plus

Mindset & Commitment:

• High agency & ownership: You develop new ideas and drive them in execution under minimal guidance

• Mission-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-end

• You’re excited to iterate quickly and build software in a fast-paced startup environment

• You want to work in-person in Munich with a higher intensity than in a 9-5 job

Your team & mentors

You will work with

• Sean (Co-Founder & CTO; Silver Medallist at the International Physics Olympiad (IPhO))

• Ben (prev. AI Engineer at Aleph Alpha)

• Mark (prev. SWE at Capital One, Cambridge Graduate)

Your mentors will be

• Rohan Ramanath (General Manager AI Product at Nubank, prev. co-founder Hyperplane)

• Daniel Ribeiro Silva (Senior Director of ML at Nubank, prev. co-founder Hyperplane)

About the interview

Step 1: Intro call

Casual intro meeting with one of the founders to get to know each other and introduce Mercura

Step 2: Technical Interview

For the take-home exercise, we’ll provide you with a task. You’ll have 3 hours to work with a dataset - exploring the data and developing prediction algorithms using AI engineering methods (e.g., LLMs, embeddings, or retrieval).

The challenge is based on a problem we’ve encountered in our day-to-day work, so it should give you a realistic sense of what the role involves.

Afterwards, you’ll present your results in a 45-minute session, where we’ll discuss your approach, reasoning, and potential improvements.

Step 3: Personal Fit

Meet another co-founder to get a feel for our culture and working style.

Step 4: 2nd Technical Interview

In this session, we’ll have a 1-hour technical discussion about different topics in AI and LLM engineering, including practical challenges when building AI-powered products and your experience working on real-world problems in this space.

Step 4: On-Site

Work alongside the entire team for a day on-site from our Munich office to fully immerse yourself in our culture and collaboration style. This on-site will be paid.

Step 5: Offer & Reference Checks

If we see a great fit, you will get an offer, including a competitive compensation package with equity participation. At the same time, we’ll ask you to provide 2–3 references so we can gather additional insights into your strengths and working style.

Why Mercura

• Join an ambitious team that feels like family: 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 like family, 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 Founders

We 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 values

Customer 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.