Max Contact Projects Graduation


I'm an independent iOS developer living near Düsseldorf in Germany. I'm developing native apps for clients since late 2010 and in between doing my own projects. I completed my MSc in computer science in spring 2013 and am since working full time as a freelancing software developer.

Inspired by high quality apps, innovative UI design and the focus on details in the iOS and Mac developer community, I've chosen to learn about and develop for Apple platforms and their native SDKs.


I'm happy to help you develop iOS, watchOS, tvOS or macOS apps of all kinds, from concept to programming and release on the App Store. I'm looking forward to hearing from you.

Just write me a mail or contact me through one of these social networks:

View Max Opitz's profile on LinkedIn   Max Opitz    

Weitere Informationen zur IT-Haftpflicht von Maximilian Opitz, Jüchen 
Maximilian Opitz
Software developer, Freelancer
41363 Jüchen near Düsseldorf, North Rhine-Westphalia, Germany
Mobile: +49 (0)170 54 24 691

Expected availability for contract work: July 2019
Remote-work preferred, on-site projects in the area of Düsseldorf and Cologne possible.
Download my complete freelancer profile here (German): PDF-Profile

To make sure you reach the most users with your app, I'm working with the experienced Android developer Roland Wimmer. This way you can be sure to profit from the most current know how on all platforms.


ADAC Camping- und Stellplatzführer

I developed the first version of this app in 2011 as a freelancer for the company mblix for the client ADAC. It's the popular german camping guide book reimagined for the iPhone and iPad (ADAC-Campingführer). Since then we rolled out completely overhauled standalone versions every year, the app was featured several times by Apple and stays in the german App Store charts pretty much all the time.

Camping sites can be found via a text search with live results, the users current location or by a pin-drop on the map. Search results can be filtered by various criteria and displayed in a list or map view. Campsites can be marked as favorites and the user can save personal notes for each of those campsites. These favorites and their notes can be accessed on any of the users iOS devices, thanks to iCloud document storage.

The camping site data is stored in a local database to minimize cellular data usage. Multithreaded Core Data is used to manage the entities of more than 10.000 camping sites, enable live search and a responsive user interface. If there are too many search results, the map view uses dynamic clustering to give the user a better overview and improve performance.

Technologies: Objective-C, Cocoa Touch, Map Kit, Core Data, iCloud, HTTP, JSON

ADAC Screenshots

POLO bikes and sportswear

POLO is one of the leading bike and sportswear shops in Germany with many stores all over the country. This is their first app for iOS and Android. We designed the apps with the biking fan in mind and tried to provide useful functions for the road: biking tour tipps, POLO store finder, POLO videos and a digital POLO club card. The user can choose his bike from a large database and create his own bike card with direct access to fitting spare parts.

I developed both apps for iOS and Android. This was my first production Android app. The apps get their data from the POLO backend and save it in a local Realm database for offline access.

Technologies iOS: Swift, Realm, iOS, Xcode, UIKit, Storyboards, Auto Layout, CocoaPods, HTTP, REST, JSON
Technologies Android: Kotlin, Realm, Android Studio, HTTP, REST, JSON, Git

ESS Screenshots

Get it on Google Play

EnergieSparSchein - Save energy with Mark Berger

The company EnergieSparSchein GmbH (energy saving certificate) follows the goal to educate people about saving energy in every day tasks and therefore save money and help the environment in the long run. The main tool for this purpose is a playful mobile app for iOS and Android, which uses gamification elements to motivate the user.

I developed the iOS app as a freelancer for the company and worked closely together with the Android and backend developer. Features of the app include a catalog of energy saving tips, local notifications to remember the user about certain actions and a tool to track readings for power, gas and water counters. These readings are displayed in a graph to directly show the user his savings over time. The user can additionally participate in quizzes to test his knowledge. He earns energy saving points for everything he does in the app and climbs up a ranking system to reflect his energy saving prowess.

The app uses heavily styled native interface elements to give it a unique and playful look without hurting the iOS interface guidelines. The app is completely written in Swift and uses multiple storyboards for it's UI. It connects to a RESTful HTTP-Backend and communicates with it via JSON. The app can be used offline thanks to a local Realm database which is periodically updated from the backend.

Technologies: Swift, Realm, Charts, iOS, Xcode, UIKit, Storyboards, Auto Layout, CocoaPods, HTTP, REST, JSON, Git

ESS Screenshots

Chain Quest

The iOS app Chain Quest is an addictive puzzle game with deep RPG mechanics. Every fight is a puzzle of attack and defense. Connect matching chips with chains to plan your next move. The longer the chains, the more powerful your actions. Level up as one of three distinct character classes, unlock skills and befriend monsters.

We developed Chain Quest as a team with the name DevBats. Adam Görtz and I did the programming, Adam Foreman made the art and Fabian Kortner the soundtrack. The game was completely developed with native Apple frameworks like Sprite Kit and UIKit.

Technologies: Objective-C, Cocoa Touch, UIKit, Sprite Kit, Core Data, UIDocument

Marktcom Screenshots

The iPhone app gives you access to the many markets of the Marktcom online platform. Markets can be found via a text search, at the users location or around a dropped pin on the map. The app communicates with a private XML-API on the Marktcom server to search and consume the market data. Search results can be viewed as a list or as pin's in a map.

Markets can be marked as favorites, which stores their data in a local database including all upcoming events, so they may be accessed even without an internet connection. Event dates can be transferred to the users calendar, the event host can be contacted and the market coordinates can be send to various navigation apps.

Technologies: Objective-C, Cocoa Touch, Map Kit, Core Data

Marktcom Screenshots

CarUnity - Car Sharing Community powered by Opel

I developed the UI and UX of the CarUnity iPhone App together with the team at Nebelhorn, enabling users to share cars with each other right from their iPhone. The App is the single interaction point for the Car Sharing Community powered by Opel, where users don’t have to worry about insurance or other complicated matters while sharing cars.

The app uses a simple and native interface for functions like sharing and finding cars, search filter, user and car profiles, chats and friends lists.

CarUnity Screenshots


2010 - 2013:
MSc in computer science at Heinrich-Heine-University Düsseldorf
Main focus: Computer networks and communication systems
Content: Network security, mobile communication, Peer-to-Peer-Systems, distributed systems, computer graphics
Master thesis: Diabetes diary - Implicit crowdsourcing of nutrition facts with a mobile app
Used technologies: Objective-C, Cocoa Touch, Core Data, Ruby on Rails (HTTP, REST, JSON)

2006 - 2010:
BSc in computer science at Heinrich-Heine-University Düsseldorf
Content: Computer science basics, algorithms and data structures, operating systems, computer networks, software development (Java, C)
Bachelor thesis: Implementation of a centralized server for traffic information
Used technologies: Java EE