MiddelkampDevelopment

Freelance app developer for iOS and Android Built with AI. Checked by me.

I'm Jop, a freelance developer in the Netherlands. I build iPhone and Android apps and the back ends behind them, with AI coding agents doing a lot of the typing. I also know where they cut corners, so nothing ships until it has passed my tests and my review.

Jop Middelkamp

From first idea to the App Store

Got an app idea? I'll take it all the way to the App Store and Google Play. I design it, build it, set up the server it needs and wire up a release pipeline that does the shipping for you.

I'm a sucker for small, sharp apps that do one thing really well. Middelkamp Development is my one-person studio, so the person you email is the person who answers for your code.

  • Flutter and Dart
  • React Native and Expo
  • TypeScript
  • C# and .NET
  • Rust
  • Docker

How I build with AI

  • Agents type, I decide

    AI coding agents write a lot of my code. Tests, CI and my review decide what ships, because AI hands you code that's almost right with total confidence.

  • No keys to production

    Agents work with test credentials only. Publishing and anything that deletes data go through me, which is where most of the famous AI disasters went wrong.

  • Extra care where it counts

    Login, payments and personal data get a line-by-line review. AI-written code still fails security checks far too often to skip that.

  • AI features that follow the rules

    Adding AI to your app? The model runs behind your own server and gets tested with evals, and Apple's consent rule and the EU AI Act's AI notice are built in from day one.

What I'm building

Next to client work, Middelkamp Development builds three products of its own. Ergates and gflow are open source. Anyone can read the code, and if you feel like helping, your bug reports and pull requests are welcome. FaceDown is a game, and its code stays closed.

  • Open source · Apache 2.0 license

    gflow

    A command-line tool for Git branches, written in Rust. It checks which branch you're on and only offers the steps that make sense there. Then it handles the merges, tags and pull requests for you, on GitHub or Azure DevOps.

    Report a bug or suggest an idea

  • Closed source · in development

    FaceDown

    A party game for 3 to 8 players around one table, each on their own phone. One player gives a clue for a picture card, the others pick a card that fits, and everybody votes. To lock in your choice, you put your phone face down.

    Coming to iPhone and Android.

Code on GitHub

Let's build your app

Need an app, or a back end for the one you already have? Send me a few lines about your idea and let's talk.