Wolfram Rittmeyer

Android and “Kotlin Multiplatform” Developer

Münster, Germany
Experience
Jan 2025 - Apr 2025
4 months
Remote

Backend and Flutter App Developer

Universität Münster

Further development of the existing (see below) citizen science app with Flutter for Android and iOS to integrate new features. Updated the backend with database migration.

Frontend:

  • Android
  • iOS
  • Flutter
  • Dart
  • Riverpod
  • Drift (DB; migrated from moor)
  • flutter_local_notifications
  • flutter_markdown
  • flutter_workmanager
  • Firebase App Testing / TestFlight
  • Google Play Console / App Store Upload

Backend:

  • Spring Boot
  • Kotlin
  • Kotlin Flow
  • PostgreSQL
  • Docker
Jul 2024 - Jun 2025
1 year
Hamburg, Germany
Remote

Android / Kotlin Multiplatform Developer

Contributed to implementing accessibility aspects and updated for the latest iOS and Android requirements. Supported onboarding and getting familiar with Compose Multiplatform.

  • Kotlin Multiplatform
  • Compose Multiplatform
  • Android
  • iOS
  • Kotlin Flow/Coroutines
  • Custom UI and Compose Multiplatform
  • Architecture Components
  • koin
  • Testing with kodein MocKMP
  • Compose UI Testing library (JetBrains variant)
  • E2E tests with Appium/UIAutomator
  • Jenkins
Jan 2024 - Jun 2024
6 months

Android and “Kotlin Multiplatform” Developer

asynkk

  • First evaluation, then prototypical implementation of Compose Multiplatform for the asynkk application.
  • Technologies:
  • Android
  • iOS
  • Desktop
  • Compose Multiplatform
  • Kotlin Multiplatform
  • Kotlin Flow/Coroutines
  • Koin
  • Ktor Client
  • SQLDelight (replaced by Room Multiplatform)
  • Voyager (MVVM + Navigation – replaced by Lifecycle Components and Navigation)
  • Arrow Core
Oct 2022 - Nov 2023
1 year 2 months

Android Automotive Developer

Valtech Mobility

  • Worked on several automotive apps.
  • Communication via AIDL with other apps (as both client and server).
  • Provided ContentProviders for other apps.
  • Technologies:
  • Android
  • Kotlin
  • Automotive
  • Coroutines/Flow
  • Android Architecture Components (ViewModel, Room)
  • Bluetooth LE
  • NSD Discovery
  • REST
  • MVVM
  • Cucumber-Android
May 2022 - Aug 2022
4 months

Android Developer

Brunch@IT

  • Developed a point-of-sale app with Jetpack Compose, integrated an external NFC reader, and added TSE-compliant storage on D-Trust SD cards (Bundesdruckerei).
  • Technologies:
  • Android
  • Kotlin
  • Jetpack Compose
  • MVVM
  • Kotlin Flow/Coroutines
  • Dagger/Hilt
  • Room
  • Retrofit
  • Coil
  • WorkManager
  • DataStore
  • Android Print API
  • cryptovision TSE
Jan 2022 - Mar 2022
3 months

Android Developer and Consultant

EnBW

  • Advised on building a new app with Jetpack Compose.
  • Helped define the app architecture and co-developed it.
  • Technologies:
  • Android
  • Kotlin
  • Jetpack Compose
  • Coroutines/Flow
  • Android Architecture Components (ViewModel, Room)
  • Dagger/Hilt
  • Multi-Module Structure
  • REST
  • MVVM
Mar 2021 - Jun 2021
4 months

Android Developer

Brunch@IT

  • Refactored an existing app towards clean code.
  • Integrated an external USB NFC reader.
  • Technologies:
  • Android
  • Kotlin
  • Java
  • MVVM
  • Kotlin Flow/Coroutines
  • Koin
  • Ktor
  • Room
Feb 2021 - Dec 2021
11 months
Münster, Germany

Backend and Flutter App Developer

WWU Münster

  • Developed a citizen science app with Flutter for Android and iOS.
  • Delivered a Dockerized backend with Spring Boot, Kotlin, and GraalVM.
  • Technologies:
  • Frontend: Android, iOS, Flutter, Dart, floor (DB), flutter_local_notifications, rest_client
  • Backend: Spring Boot, Kotlin, Kotlin Flow, GraalVM, PostgreSQL, Docker
Jan 2021 - Aug 2021
8 months

Android Trainer and Coach

medienmonster GmbH

  • Initial training and coaching of the client before the Android project began.
  • Ongoing coaching throughout the project.
  • Technologies:
  • Android
  • Kotlin
  • MVVM
  • Android Architecture Components
  • Koin
  • Room
  • ExoPlayer
Oct 2020 - Sep 2021
1 year

Android and iOS / Kotlin Multiplatform Developer

Dawesys

  • Laid the foundation for a Kotlin Multiplatform–based app.
  • Implemented use cases in Kotlin with Kotlin Flow and Coroutines.
  • Built the iOS interface with SwiftUI, MVVM, and Combine.
  • Technologies:
  • Android
  • iOS
  • Kotlin
  • Swift
  • MVVM
  • Jetpack Compose
  • SwiftUI
  • Combine
  • Kotlin Multiplatform
  • Kotlin Flow/Coroutines
  • Koin
  • Ktor
  • SQLDelight
Jul 2020 - Nov 2020
5 months

Android Developer

Celeski

  • Ported an iOS app to Android, following Material Design guidelines.
  • Technologies:
  • Android
  • Kotlin
  • Coroutines
  • Android Architecture Components (ViewModel, LiveData, Room)
  • TDD
  • Espresso
  • REST
  • MVVM
  • Bitbucket Pipelines
Oct 2019 - Apr 2023
3 years 7 months

Android Developer

Honigmann

  • Continued development and refactoring of an Android app for communicating with a Bluetooth IoT device in the industrial sector.
  • Helped implement an Android-typical design and refactored for better architecture and higher test coverage.
  • Technologies:
  • Android
  • Kotlin
  • Coroutines
  • Android Architecture Components (ViewModel, LiveData, Room)
  • Bluetooth
  • REST
  • MVVM
  • Bitbucket Pipelines
Aug 2019 - Oct 2021
2 years 3 months

Java Microservice Developer

Finanzbranche

  • Long-term support of a team implementing two microservices.
  • Assisted with OAuth security using Nimbus-JOSE+JWT.
  • Technologies:
  • Java
  • Docker
  • Kubernetes/OpenShift
  • Jenkins
  • Kafka
  • Spring Boot
  • Grafana
  • Prometheus
  • JWT
  • Pact
  • Newman
  • JavaScript
  • Angular
Aug 2019 - Oct 2019
3 months

Android and iOS Developer

Dawesys

  • Developed an app for choirs.
  • Advised on building the REST API.
  • Technologies:
  • Kotlin
  • Swift
  • Room
  • ViewModel
  • LiveData
  • Core Data
  • REST
  • MVVM
May 2019 - Aug 2019
4 months

iOS Developer

menadwork

  • Advised and supported porting and further development of an existing cross-platform app to iOS (see next Android project).
  • Technologies:
  • iOS
  • Swift
  • Core Data
  • REST
  • RxSwift
  • MVVM
Dec 2018 - Apr 2019
5 months

Android Developer

menadwork

  • Ported and then extended an existing cross-platform app on Android.
  • Modularized features to reuse for similar apps.
  • Technologies:
  • Android
  • Kotlin
  • Coroutines
  • Room
  • SQLite
  • Bluetooth
  • REST
  • Espresso
  • TDD
  • MVP
  • GitLab CI Pipeline
Jun 2018 - Aug 2018
3 months

Android Developer

Jauernig

  • Ported an existing Visual Basic Windows app to Android.
  • Helped implement Android-typical design.
  • Technologies:
  • Android
  • Kotlin
  • Room
  • SQLite
  • Firebase
  • MVP
Jun 2018 - Aug 2018
3 months

Android Developer

Tagify

  • Rebuilt the existing app (see below) on a new Firebase-based backend.
  • Technologies:
  • Android
  • Java
  • Firebase
  • RxJava
Feb 2018 - May 2018
4 months

Android Developer

If-com

  • Communicated with a Bluetooth device.
  • Displayed data as a system overlay.
  • Technologies:
  • Android
  • Kotlin
  • Bluetooth
  • Retrofit
  • SQLite
  • Firebase
  • RxJava
May 2016 - Dec 2016
8 months
Leverkusen, Germany

Android and iOS Developer

Nabu Naturschutzstation Leverkusen

  • Advised on appropriate designs for each platform.
  • Used analogous RxJava and RxSwift flows.
  • Built custom views for games and quizzes aimed at young teens.
  • Technologies:
  • Android
  • Kotlin
  • SQLite
  • Retrofit
  • Firebase
  • RxJava
  • iOS
  • Swift
  • Alamofire
  • Core Data
  • Core Location
  • RxSwift
Feb 2016 - May 2016
4 months

Android Developer

Flaschenpost

  • Built a delivery app for drivers.
  • Integrated special hardware for barcode scanning (Zebra hardware scanner with proprietary interface).
  • Handled location and integrated maps and navigation.
  • Technologies:
  • Android
  • Java
  • SQLite
  • Retrofit
  • Firebase
  • Zebra Barcode Scanner library
  • MVP
Dec 2015 - Sep 2019
3 years 10 months

Android and iOS Software Developer

Versicherung

  • Long-term support of a team building and extending an app for expense tracking.
  • OAuth integration.
  • Advised and implemented push solution.
  • Technologies:
  • Android
  • iOS
  • Java
  • Swift
  • SQLite
  • Retrofit
  • Alamofire
  • Firebase Remote Config
  • OAuth
  • Core Data
  • Jenkins build pipeline
  • Swagger
May 2015 - Sep 2015
5 months

Android Developer

Tagify

  • Ported an iOS app to Android.
  • Advised on adapting iOS patterns to Android-specific solutions.
  • Stored data initially in SQLite after fetching from a custom backend.
  • Later project rebuilt on Firebase backend.
  • Technologies:
  • Android
  • Java
  • SQLite
  • Retrofit
  • Firebase
  • RxJava
  • MVP
May 2014 - Dec 2015
1 year 8 months

Android Software Developer

fileee

  • Long-term support of a team building and extending an app for document capture and management.
  • Introduced MVP and Dagger.
  • Technologies:
  • Android
  • Java
  • SQLite
  • Retrofit
  • Dagger
  • MVP

Android Trainer

  • 3 or 5 days twice a year for about two weeks total.
  • Intro to Android basics with own script.
  • Technologies:
  • Android
  • Jetpack Compose
  • Lifecycle
  • Retrofit
  • Picasso
  • Room
  • ViewModel
  • LiveData
  • Navigation Components
  • MVVM
  • Testing
  • SQLite

Freelancer

  • Worked as an Android freelancer on various projects.
  • Helped a client move their existing app to an MVP-based architecture, decoupling components and improving maintainability.
  • “Wolfram is my Android guy” (Brian Walton from Bevgem LLC).
  • Blogs extensively about Android topics on Grokking Android.
  • Recognized by Google as a Google Developer Expert for Android.
  • Technologies:
  • Android
  • iOS
  • Java
  • Kotlin
  • Swift
  • Architecture Components
  • Kotlin Coroutines
  • Spring Boot
  • SQL
  • Core Data
  • Firebase
  • Kubernetes

Mobile Developer

GAD eG

  • Worked on the core of the online banking system.
  • Developed the content management system for financial institutions.
  • Built Android and iOS apps as a mobile developer.
  • Collaborated closely with usability experts to create user-friendly solutions.
  • Suggested quick wins and compared them to costlier options with lower benefit.
  • Technologies:
  • Java
  • Android
  • iOS
  • Swift
  • JSP
  • Taglibs
  • Content Repositories

Shop Developer

ICN GmbH

  • Helped find solutions and workarounds for issues in the underlying shop system.
  • Technologies:
  • Java
  • JSP
  • Internolix
  • Oracle SQL

Java Developer

proPlant GmbH

  • Worked as a Java developer on precision farming solutions.
  • Designed the architecture of a new web solution for SensorOffice to quickly meet customer requirements and go live without sacrificing maintainability.
  • Technologies:
  • Java
  • PostgreSQL
  • Oracle PL/SQL
  • JSP

Software Developer

zefa visual media GmbH

  • Worked on the zefa Lightbox system for zefa end customers.
  • Responsible for the database and DB abstraction layer.
  • Used PostgreSQL expertise to optimize the database and give customers fast access to content.
  • Technologies:
  • Java
  • PostgreSQL
  • JSP
  • EJB
  • MBeans
Summary

Passionate developer with many years of experience in software development with Java and Kotlin. Deep knowledge in Android and iOS and backend development. Committed to robust solutions focused on the end user. Always interested in new technologies. He sees the need to learn and the fast pace of software industry as a key advantage over other activities.

Speaks at conferences like Droidcon London, Devoxx Antwerp, Android Makers Paris, and MobileTechCon Berlin.

Active member and co-organizer of the Google Developer Group Düsseldorf.

Blogs on Grokking Android and is active in the Android and Voice App community on Twitter.

Loves open source. Was a committer on Apache JMeter and GlassFish.

Languages
German
Native
English
Advanced
Education

Westfälische Wilhelms University, Münster

Political Science · Münster, Germany

Certifications & licenses

Google Developer Expert for Android

Google

Linux Professional Institute Level 1 Certification

Linux Professional Institute

Sun Certified Enterprise Component Developer

Sun

Sun Certified Java Programmer

Sun

Sun Certified Web Component Developer

Sun

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