Mission

More than €1.35 trillion was invested in construction across Europe in 2025. Yet before any project can be built, contractors have to turn complex documents, supplier offers, product data, and labor assumptions into a reliable offer. Much of this work is still manual and fragmented across spreadsheets and legacy system: slowing down the process, tying up scarce experts, and putting margins at risk.

We are building 90/10 because construction companies need one place where all the data and decisions behind an offer come together. Our ambition is to become the single platform for calculation across the construction industry: starting with technical building equipment (TBE).

Our current pipeline contains meaningful ****test and pilot opportunities, with companies already in onboarding or an active test phase. Now we are looking for our first engineer to build the product and company with us.

Moritz & Änni

What You’ll Work On

You’ll ship real product alongside the two founders. We’re looking for an engineer who wants to build 90/10 with us from an early stage.

• Core product: Connect unstructured documents with different data sources, reliable and traceable.
• AI systems: Decide what should be model-driven, rule-based, or confirmed by a human.
• Full-stack product: Improve performance and usability for real tenders with hundreds or thousands of positions.
• Engineering foundations: Shape our architecture, security standards, development workflow, and future engineering team.

Who We’re Looking For

• You have built, operated and owned a product end to end, ideally in an early-stage B2B environment.
• You use AI heavily without outsourcing your judgement to it.
• You can turn an unclear customer problem into a simple product decision and take responsibility for what happens after deployment
• You do not need a construction background but the curiosity to understand why a unit, price basis, material surcharge, or labor-time assumption can move an offer by five figures

Technical

• 3+ years of experience in software engineering
• TypeScript-only: Tanstack / React, Convex and Mastra. Convex experience is useful, but strong fundamentals matter more
• Care about types, clear interfaces and sensible data models