Celebrating 10 Years!

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App Development


Using Spotify but your friend’s on Apple? Not a problem with Earbuds! Just send and we’ll find the matching song for them. No more sending YouTube links with annoying ads. No more 🤹 multiple apps.

Samuel was responsible for building and maintaining most of the iOS app as well as parts of the Go backend API used to provide data for the app. This included extensive work with the Apple Music and Spotify web and mobile APIs as well as integrations with ChatGPT and Stream.


Nebula is a place to experiment, explore, and tailor our content to our audience, not to unskippable ads or recommendation algorithms.

Samuel was responsible for bringing in-app-purchase subscriptions to the iOS app, now u sed by thousands of customers. He also helped improve launch and runtime performance as well as implement new features throughout the year.


Zenly is a live map of your friends and family. It’s the most fun way to meet up — or just see what’s up! — so you can feel together, even when you're apart.

Samuel was responsible for fixing up the app's support for right-to-left languages like Arabic. This meant fixes across over 300k lines of code in a project run by a fairly large team.


OYA is an app to allow easy access to cell data. It seeks to simplify the signup and legal process to provision eSIM cards. No more needing to visit a store and do paperwork for a sim when you travel!

Samuel was responsible for overhauling the early version of the app and preparing it to support multiple countries and devices.


Fairtiq is an app to simplify travel on public transport and trains. Rather than buying tickets and passes, people can track their travel with the app. Fairtiq works behind the scenes to find the cheapest fare for your travels.

Samuel was responsible for overhauling the underlying SDK and build version 4.0 of the app on top of it. It is well-tested and in the hands of people all over Switzerland and parts of Austria.


Human is an all-day activity & calorie tracker that inspires you to move 30 minutes or more, every day.

Samuel was responsible for improving performance, improving the architecture of the app, training the existing developer, and helping to add their latest social features.


The official app of the primary airport of the Netherlands. Samuel was the lead iOS engineer on a team with iOS engineers, Android engineers, back-end engineers, designers, a scrum master, and a product manager. They produced a clean rewrite of the app to deliver a fast and smooth experience for frequent fliers.


A pleasant experience for buying tickets to major museums and venues in cities around Europe (and expanding). Samuel helped a recent convert to iOS grow and improve the app over the course of 4 months. This included new features as well as structural improvements to make things more consistent and easier to deal with. All crashes were eliminated.


I am also available for training. If your existing team is having trouble, I'm happy to help get things back on-track. We can discuss frameworks, development processes, problem solving strategies, multi-threading issues, networking troubles, etc.

The App Academy

The App Academy is a 12-week bootcamp here in Amsterdam to help people become iOS developers. I taught one of these for 7 new iOS developers.

Samenwerken: F3PiX

F3piX is an app by a local Dutch student. Without much previous programming experience, she developed this app to showcase some local Dutch photographers.

Let's do this!

We are located in Amsterdam and would be happy to discuss how we can help you.

The best way to get things started is to drop us a line at samuel@roundwallsoftware.com.