(Senior) Fullstack 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 role

As a Full-Stack Engineer, you will play a key role in building AI systems end-to-end. This is a fast-paced, hands-on role for engineers with high agency, strong technical depth and founder mindset. We’re looking for experienced builders with a strong product mindset and a track record of shipping complex web applications.

If you are a builder who thrives at the intersection of full-stack development and AI - this is your opportunity to working alongside a team of stellar engineers and shape how users interact with AI.

What you will be working on

• Core Engineering: Design and build high-performance, reliable systems that power Mercura’s AI products and ensure scalability.

• End-to-End Ownership: Own features end-to-end from architecture and implementation to deployment, monitoring, and iteration.

• Backend & APIs: Develop scalable APIs and backend systems that support evolving AI capabilities and product growth.

• Product Engineering: Work closely with users and the product team to translate real-world workflows into clear product and engineering decisions.

• Rapid Iteration: Ship improvements quickly through fast iteration cycles and pragmatic engineering decisions.

• AI Integration: Contribute to LLM engineering and AI systems, collaborating with the team on how models are integrated into the product.

• Technical Architecture: Help shape the overall system architecture, deployment strategy, and engineering tooling across the stack.

What we offer:

• Steepest 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 for

Technical Skills & Experience:

• Strong experience with full-stack software engineering (React, Typescript, Python)

• Proven track record of architecting and building complex, production-grade software systems

• Strong understanding of improving system performance, reliability, and scaling challenges in production environments

• Cloud & DevOps: Experience with containerization (Docker), cloud infrastructure (Azure/AWS/GCP), and infrastructure as code (Terraform).

• Experience integrating LLMs, AI systems, or large-scale data pipelines into production software is a big plus

Commitment & Mindset:

• 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 treat your work as a top priority, and you’re fully committed to 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))

• 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 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 Kolya Krafeld to get to know each other and introduce Mercura

Step 2: Technical Take-Home: For the take-home exercise, we’ll provide you with a task. You’ll have a 3 hours to design and implement a small application end-to-end including the frontend, backend, and any supporting components you consider necessary. The goal is to build a functional solution to a problem similar to those we encounter in our day-to-day work. This should give you a realistic sense of the kinds of systems we build and how we approach product development.

Step 3: Deep-Dive Interview: You'll present your results in a 45-minute session, where we’ll discuss your design decisions, implementation choices, and potential improvements.

Step 4: On-Site: Work alongside the team for a half-day on-site from our Munich office to fully immerse yourself in our culture and collaboration style.

Step 5: Offer & Reference Checks: If we see a great fit, you will get an offer. 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.

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.