Megunto
The mobile version of an existing exam-prep platform for doctors and medical students, with AI-assisted evaluation.
Senior Flutter developer in Berlin.
I get stuck apps shipped – and strengthen teams that are serious about Flutter. Ten-plus years of experience, seven of them at Appsfactory building for Vattenfall, Deutsche Bahn and Porsche. Co-founder and CTO of Kiezpass, sold in 2025.
Three things I do
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01
Stuck apps
The app is almost done but won't get into the store. The developer left. The prototype works, but nobody can make it production-ready. I take over existing Flutter codebases, resolve App Store and Google Play rejections, and move FlutterFlow projects into clean Flutter code.
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02
Xamarin → Flutter
Xamarin has been end-of-life since 2024. If your backend is .NET and your app is Xamarin, I migrate it to Flutter – and your backend team won't have to explain to anyone what a DTO is. I've built Xamarin apps and .NET backends on Azure myself.
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03
Senior & lead in your team
Architecture, code reviews, release process, mentoring – for teams in energy, mobility and healthcare where German, data protection and on-site presence matter. Full-time engagements from six months.
Track record
Clients at Appsfactory
- Vattenfall
- Deutsche Bahn
- Porsche
- Swiss Re
- Lidl
- Bayer 04
- Burda Verlag
- GU Verlag
Numbers
- 10+ years in software
- 6 apps shipped since 2021
- 1 company founded and sold
About
I'm Sebastian, a graduate engineer in multimedia technology and a software developer for over ten years. Seven of those at Appsfactory in Leipzig and Berlin: backend with .NET and Azure first, then Xamarin and native apps, most recently as one of three tech leads for a team of 40. In 2024 I co-founded Kiezpass, built it as CTO and sold it in 2025. I've been freelancing since 2021 and have shipped six apps from architecture to store release.
I like working in teams, full-time and for longer periods too. What I don't do: make promises I can't keep. If your app can't be live in eight weeks, I'll say so in the first call.
Stack
Common questions
How quickly can you start?
From October 2026. For a takeover or a store-review case, one day of onboarding is usually enough before I give an assessment.
Do you work on site in Berlin?
Yes. I live in Berlin and come to the office for workshops, onboarding or regular on-site days. Remote engagements anywhere in Germany work as well.
Do you take over code someone else wrote?
Yes, that's a focus. I look at the codebase, the build pipeline and the store accounts and tell you what needs to happen in which order – before we talk scope and effort.
Why Flutter instead of .NET MAUI for a Xamarin app?
Both are possible, and I'll tell you when MAUI is the better choice. Flutter usually wins on UI ambition, team availability and web targets. Your .NET backend stays untouched either way.
How do you bill?
By day rate, weekly or monthly. No fixed price, except for a clearly scoped initial assessment.
Contact
Tell me briefly what it's about. I usually reply within one working day with a first assessment.