Founding iOS Engineer (m/f/d) / Ferto AI

About us

Most labs still count cells under a microscope by hand. It's slow, repetitive, and error-prone. We're replacing that manual work with software. By combining a standard microscope with a smartphone, we run computer vision models that locate, track, and measure cells automatically in real time. We're starting with semen analysis and expanding to other routine microscopic samples. Based in Berlin, we're a small, well-funded team founded in 2026 operating in stealth. Our goal is to make automated, reliable diagnostic analysis accessible on any phone connected to a microscope.

The role

We're looking for an iOS engineer who loves the camera. Our app turns an iPhone on a microscope into a lab instrument, and the hard problems live on the device: holding focus on a moving sample, running computer vision in real time, and capturing a recording precise enough for a clinical result. On top of that, the app has to be simple enough for a technician in a busy lab. You'll own it end to end, together with the founders.

What you'll do

• Own the app end to end, from architecture to release.
• Push the iPhone camera and on-device models to their limits, so every recording is good enough to analyse.
• Design the capture workflow with lab staff, so technicians get it right the first time.
• Spend time in the lab, measure what works, and decide what to build next.

What you bring

• Camera depth. You've built on the iOS camera stack, not just used it: AVFoundation with manual focus, exposure and white balance, and real-time frame processing. You know where the hardware's limits are.
• On-device ML. You've run models on the phone and made them fast: CoreML and Vision, quantisation, the Neural Engine, profiling with Instruments.
• Apps you've owned. You've shipped iOS apps in Swift and SwiftUI and owned them in production. You design an architecture one engineer can carry, and you can explain the trade-offs behind it.
• Product and UX sense. You turn a messy real-world workflow into something simple, and you test it with the people who use it.
• Built for real conditions. Offline-first, background uploads, interruptions, data protection. The app works when the network doesn’t.
• Beyond the app. iOS is your home, but when the app needs it, you read the backend and change an API yourself.
• Correctness. You validate with numbers, not by eye. Tests are part of the feature.
• You reproduce bugs first and fix the cause, not the symptom.
• AI-native engineering. Coding agents are part of your daily work. You give them good context, split work into reviewable steps, and stand behind every line you ship.
• Ownership. You help shape the roadmap, push back on weak ideas, set your own priorities and raise problems early. Nobody has to chase you.

Nice to have

• Optics or microscopy imaging.
• Apps for professional users: lab, field, clinical or enterprise.
• Regulated environments with audits: medical devices, health, finance.

What we offer

• Ownership from day one.
• As a founding engineer, you're part of the company through our virtual share option plan (VSOP).
• You grow with us.
• You help build the company from the start, and as it grows, your role grows with it.
• Real influence.
• You decide how we build software, and you shape the engineering team we build.
• A competitive salary. We share the range in our first conversation.
• A product that matters: a medical device for real clinics, built together with clinicians and lab staff.
• Flexible hours and office days.
• We work from Berlin and meet in person regularly, up to several days a week.
• This isn't a fully remote role.
• English is our working language.
• German isn't required.
• We sponsor the EU Blue Card if you're moving to Berlin.