Full-Stack Engineering Intern

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 a Full-Stack Engineering Intern , 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.

We hold interns to the same standard as full-time hires: We only bring on people we trust to take ownership of projects independently and whom we would want to work with long-term.

If you are a passionate builder who thrives at the intersection of full-stack development & AI - this is your opportunity to working alongside a team of the most 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

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.

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

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

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 e