Wolfram Rittmeyer - Backend and Flutter App Developer

Q: Where is Wolfram based?

Wolfram is based in Münster, Germany .

Q: What languages does Wolfram speak?

Wolfram speaks the following languages: German (Native), English (Advanced) .

Q: How many years of experience does Wolfram have?

Wolfram has at least 11 years of experience. During this time, Wolfram has worked in at least 15 different roles and for 20 different companies . The average length of individual experience is 5 months . Note that Wolfram may not have shared all experience and actually has more experience.

Q: What is Wolfram's latest experience?

Wolfram's most recent position is Backend and Flutter App Developer at WWU Münster .

Q: What companies has Wolfram worked for in recent years?

In recent years, Wolfram has worked for WWU Münster , Starfinanz , asynkk , Valtech Mobility , and Dawesys .

Q: Which industries is Wolfram most experienced in?

Wolfram is most experienced in industries like Information Technology (IT) , Banking and Finance , and Insurance . Wolfram also has some experience in Manufacturing , Education , and Automotive .

Q: Which business areas is Wolfram most experienced in?

Wolfram is most experienced in business areas like Information Technology (IT) , Product Development , and Quality Assurance (QA) . Wolfram also has some experience in Research and Development (R&D) and Logistics .

Q: Which industries has Wolfram worked in recently?

Wolfram has recently worked in industries like Banking and Finance , Manufacturing , and Information Technology (IT) .

Q: Which business areas has Wolfram worked in recently?

Wolfram has recently worked in business areas like Information Technology (IT) , Product Development , and Quality Assurance (QA) .

Recommended expert

Münster, Germany

Experience

Jan 2025 - Apr 2025

4 months

Backend and Flutter App Developer

WWU Münster

Further development of the existing citizen science app with Flutter for Android and iOS to integrate new features.
Updated the backend, including database migration.
Used Android, iOS, Flutter, Dart, Riverpod, Drift (migration from moor), flutter_local_notifications, home_widget, flutter_markdown, and flutter_workmanager.
Backend development with Spring Boot, Kotlin, Kotlin Flow, GraalVM, PostgreSQL, and Docker.
Used Firebase App Testing, Testflight, as well as Google Play Console and App Store upload.

Jul 2024 - Present

1 year 8 months

Android / Kotlin Multiplatform Developer

Starfinanz

Contributed to implementing accessibility requirements.
Updated the app to the latest iOS and Android requirements.
Developed with Android, iOS, Kotlin Multiplatform, Kotlin Flow/Coroutines, custom UI, and Compose Multiplatform.
Used Architecture Components, Swift, Koin, and testing with mockk.
Performed end-to-end tests with Appium/UIAutomator and integrated them in Jenkins.

Jan 2024 - Apr 2024

4 months

Fullstack Developer

asynkk

Implemented the asynkk application with REST endpoints in the backend.
Integrated Userfront for authentication and JWT handling.
Backend development with Spring Boot, Kotlin, Kotlin Flow, JPA/Hibernate, Docker, Bitbucket Pipelines, and PostgreSQL.
Frontend development with React and Jest.

Oct 2022 - Nov 2023

1 year 2 months

Android Automotive Developer

Valtech Mobility

Worked on multiple Android Automotive apps.
Implemented interprocess communication via AIDL, both as a client and a server app.
Provided content providers for other apps.
Used Android, Kotlin, Automotive, Coroutines/Flow, and Android Architecture Components (ViewModel, Room).
Used Bluetooth LE, NSD discovery, REST, MVVM, and Cucumber-Android.

Sep 2022 - Mar 2023

7 months

Go / React Developer

Dawesys

Built a backend with Go.
Developed the frontend with React.
Used Go, Gin, Gorm, httptest, PostgreSQL, Linux, JavaScript, React, and Jest.

May 2022 - Aug 2022

4 months

Android Developer

Brunch@IT

Developed a point-of-sale app with Jetpack Compose.
Integrated an external NFC reader.
Implemented TSE-compliant storage on D-Trust SD cards (Bundesdruckerei).
Used Android, Kotlin, Jetpack Compose, MVVM, Kotlin Flow/Coroutines, Dagger/Hilt, Room, Retrofit, Coil, WorkManager, DataStore, Android Print API, and cryptovision TSE.

Jan 2022 - Mar 2022

3 months

Android Developer and Consultant

EnBW

Advised on the implementation of a new Android app with Jetpack Compose.
Collaborated on defining and implementing the app architecture.
Supported the ongoing development of the application.
Used Android, Kotlin, Jetpack Compose, Coroutines/Flow, Android Architecture Components (ViewModel, Room), Dagger/Hilt, multi-module structure, REST, and MVVM.

Mar 2021 - Jun 2021

4 months

Android Developer

Brunch@IT

Refactored an existing Android app towards Clean Code.
Integrated an external USB NFC reader.
Used Android, Kotlin, Java, MVVM, Kotlin Flow/Coroutines, Koin, Ktor, and Room.

Feb 2021 - Dec 2021

11 months

Backend and Flutter Developer

WWU Münster

Developed a citizen science app with Flutter for Android and iOS.
Provided a dockerized backend with Spring Boot, Kotlin, and GraalVM.
Used Android, iOS, Flutter, Dart, floor (DB), flutter_local_notifications, and rest_client on the frontend.
Used Spring Boot, Kotlin, Kotlin Flow, GraalVM, PostgreSQL, and Docker in the backend.

Jan 2021 - Aug 2021

8 months

Android Trainer and Coach

medienmonster GmbH

Provided initial training and coaching to the client before the Android project started.
Provided continuous coaching throughout the project implementation.
Shared best practices for Android, Kotlin, MVVM, Android Architecture Components, Koin, Room, and ExoPlayer.

Oct 2020 - Sep 2021

1 year

Android and iOS Developer

Dawesys

Created the foundation for a Kotlin multiplatform app.
Implemented the use cases in Kotlin using Kotlin Flow and coroutines.
Built the iOS interface with SwiftUI, MVVM and Combine.
Used Android, iOS, Kotlin, Swift, MVVM, Jetpack Compose, SwiftUI, Combine, Kotlin Multiplatform, Kotlin Flow/Coroutines, Koin, Ktor and SQLDelight.

Jul 2020 - Nov 2020

5 months

Android Developer

Celeski

Ported an iOS app to Android following Material Design guidelines.
Used Android, Kotlin, coroutines, Android Architecture Components (ViewModel, LiveData, Room), TDD, Espresso, REST, MVVM and Bitbucket Pipelines.

Oct 2019 - Apr 2023

3 years 7 months

Android Developer

Honigmann

Further developed and refactored an existing Android app to communicate with a Bluetooth IoT device in the industrial sector.
Helped implement an Android-style design.
Refactored the app towards a better architecture with higher test coverage.
Used Android, Kotlin, coroutines, Android Architecture Components (ViewModel, LiveData, Room), Bluetooth, REST, MVVM and Bitbucket Pipelines.

Sep 2019 - Oct 2020

1 year 2 months

Backend Developer

Bankensystem

Supported the development of a Spring Boot microservice connecting to a third-party identity provider.
Used Java, Spring, JPA/Hibernate, OpenAPI, Oracle DB, Jenkins, Kubernetes/OpenShift, Angular and RxJS.

Aug 2019 - Oct 2019

3 months

Android and iOS Developer

Dawesys

Developed an app for choirs.
Advised on creating the REST API.
Used Kotlin, Swift, Room, ViewModel, LiveData, Core Data, REST and MVVM.

May 2019 - Aug 2019

4 months

iOS Developer

menadwork

Consulting and support for porting and further development of an existing cross-platform app to iOS.
Used iOS, Swift, Core Data, REST, RxSwift, and MVVM.

Dec 2018 - Apr 2019

5 months

Android Developer

menadwork

Porting and further development of an existing cross-platform app to Android.
Modularizing the app to reuse components for similar applications.
Used Android, Kotlin, Coroutines, Room, SQLite, Bluetooth, REST, Espresso, TDD, MVP, and the GitLab CI pipeline.

Aug 2018 - Oct 2021

3 years 3 months

Java Microservice Developer

Finance sector

Long-term support of a team in implementing various microservices.
Assisted with OAuth security using Nimbus-JOSE+JWT.
Used Java, Docker, Kubernetes/OpenShift, Jenkins, Kafka, Spring Boot, Grafana, Prometheus, JWT, Pact, Newman, JavaScript, and Angular.

Jun 2018 - Aug 2018

3 months

Android Developer

Jauernig

Porting an existing Visual Basic Windows app to Android.
Helped implement a typical Android design.
Used Android, Kotlin, Room, SQLite, Firebase, and MVP.

Jun 2018 - Aug 2018

3 months

Android Developer

Tagify

Rebuilt an existing Android app with a new Firebase-based backend.
Used Android, Java, Firebase, and RxJava.

Feb 2018 - May 2018

4 months

Android Developer

If-com

Developed an Android app for communication with a Bluetooth device.
Displayed received data as a system overlay.
Used Android, Kotlin, Bluetooth, Retrofit, SQLite, Firebase, and RxJava.

May 2016 - Dec 2016

8 months

Android and iOS Developer

Nabu Naturschutzstation Leverkusen

Advised on implementing platform-specific, appropriate designs for Android and iOS.
Used analogous RxJava and RxSwift flows.
Developed custom views to display games and quizzes for young teens.
Used Android, Kotlin, SQLite, Retrofit, Firebase, RxJava, iOS, Swift, Alamofire, Core Data, Core Location, and RxSwift.

Feb 2016 - May 2016

4 months

Android Developer

Flaschenpost

Developed a delivery app for drivers.
Integrated specialized hardware for barcode scanning (Zebra barcode scanner with a proprietary interface).
Implemented localization, maps integration, and navigation.
Used Android, Java, SQLite, Retrofit, Firebase, the Zebra barcode scanner library, and MVP.

Dec 2015 - Sep 2019

3 years 10 months

Software Developer Android and iOS

Versicherung

Provided long-term support to a team in implementing and extending an app for capturing receipts.
Connected the app using OAuth.
Advised on and implemented the push notification solution.
Used Android, iOS, Java, Swift, SQLite, Retrofit, Alamofire, Firebase Remote Config, OAuth, Core Data, Jenkins build pipeline, and Swagger.

May 2015 - Sep 2015

5 months

Android Developer

Tagify

Ported an iOS app to Android.
Advised on translating iOS-specific patterns into Android-specific solutions.
Initially handled data storage via SQLite after retrieving it from a custom backend.
Prepared for a later migration to a Firebase-based backend.
Used Android, Java, SQLite, Retrofit, Firebase, RxJava, and MVP.

May 2014 - Dec 2015

1 year 8 months

Android Software Developer

fileee

Long-term support of a team in implementing and expanding an app for capturing and managing documents.
Introduced MVP architecture and Dagger in the Android app.
Used Android, Java, SQLite, Retrofit, Dagger, and MVP.

Freelancer

Worked as an Android freelancer on various projects.
Helped a client migrate an existing app to an MVP-based architecture to decouple components and improve maintainability.
Extensive long-term blogging on Android topics on Grokking Android.
Recognized as a Google Developer Expert for Android.
Used Android, iOS, Java, Kotlin, Swift, Architecture Components, Kotlin Coroutines, Spring Boot, SQL, Core Data, Firebase, and Kubernetes.

Software Developer

GAD eG

Contributed to the core of an online banking system.
Developed the content management system for financial institutions.
Worked as a mobile developer for Android and iOS apps.
Collaborated closely with usability experts to develop user-friendly solutions.
Identified and implemented quick wins compared to more costly measures with lower benefits.
Used Java, Spring, JPA/Hibernate, Android, iOS, Swift, JSP, Taglibs, and content repositories.

Shop Developer

ICN GmbH

Developed and customized shop solutions.
Developed solutions and workarounds for issues in the underlying shop system.
Used Java, JSP, Internolix, and Oracle SQL.

Java Developer

proPlant GmbH

Developed precision farming solutions as a Java developer.
Designed the architecture for a new web solution for SensorOffice to quickly meet customer requirements and enable go-live.
Ensured the maintainability of the application despite the fast implementation speed.
Used Java, PostgreSQL, Oracle PL/SQL, and JSP.

Software Developer

zefa visual media GmbH

Developed the zefa lightbox system for end users.
Responsible for the database and database abstraction layer.
Optimized the PostgreSQL database to speed up content access for customers.
Worked with Java, PostgreSQL, JSP, EJB, and MBeans.

Industries Experience

See where this freelancer has spent most of their professional time. Longer bars indicate deeper hands-on experience, while shorter ones reflect targeted or project-based work.

Experienced in Information Technology (7 years), Banking and Finance (5 years), Insurance (4 years), Manufacturing (3.5 years), Education (1 year), and Automotive (1 year).

Information Technology

Banking and Finance

Insurance

Manufacturing

Education

Automotive

Business Areas Experience

The graph below provides a cumulative view of the freelancer's experience across multiple business areas, calculated from completed and active engagements. It highlights the areas where the freelancer has most frequently contributed to planning, execution, and delivery of business outcomes.

Experienced in Information Technology (11.5 years), Product Development (8 years), Quality Assurance (1.5 years), Research and Development (1 year), and Logistics (0.5 years).

Information Technology

Product Development

Quality Assurance

Research and Development

Logistics

Summary

Passionate developer with many years of experience in software development with Java and Kotlin. Deep knowledge in backend and app development.

Committed to robust solutions that focus on the end user. Always interested in new technologies. He sees the need to learn and the fast pace of development in the software industry as a major advantage over other fields.

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

Active member and co-organizer of the Google Developer Group Düsseldorf. Blogs on Grokking Android and is active in the Android community.

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

Since 2016, Google Developer Expert in Android.

Skills

Java > 20 Years
Android > 10 Years
Kotlin 7 Years
Ios / Swift 8 Years
Javascript 8 Years
Typescript 5 Years
Go 2 Years

Languages

German

Native

English

Advanced

Education

University of Münster

M.A. · Political Science · Münster, Germany

Certifications & licenses

Linux Professional Institute: Level 1 Certification

Sun Certified Enterprise Component Developer

Sun Certified Java Programmer

Sun Certified Web Component Developer

Profile

Created

May 2024

Last Update

June 2025

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Frequently asked questions

Do you have questions? Here you can find further information.

Where is Wolfram based?

Wolfram is based in Münster, Germany.

What languages does Wolfram speak?

Wolfram speaks the following languages: German (Native), English (Advanced).

How many years of experience does Wolfram have?

Wolfram has at least 11 years of experience. During this time, Wolfram has worked in at least 15 different roles and for 20 different companies. The average length of individual experience is 5 months. Note that Wolfram may not have shared all experience and actually has more experience.

What roles would Wolfram be best suited for?

Based on recent experience, Wolfram would be well-suited for roles such as: Backend and Flutter App Developer, Android / Kotlin Multiplatform Developer, Fullstack Developer.

What is Wolfram's latest experience?

Wolfram's most recent position is Backend and Flutter App Developer at WWU Münster.

What companies has Wolfram worked for in recent years?

In recent years, Wolfram has worked for WWU Münster, Starfinanz, asynkk, Valtech Mobility, and Dawesys.

Which industries is Wolfram most experienced in?

Wolfram is most experienced in industries like Information Technology (IT), Banking and Finance, and Insurance. Wolfram also has some experience in Manufacturing, Education, and Automotive.

Which business areas is Wolfram most experienced in?

Wolfram is most experienced in business areas like Information Technology (IT), Product Development, and Quality Assurance (QA). Wolfram also has some experience in Research and Development (R&D) and Logistics.

Which industries has Wolfram worked in recently?

Wolfram has recently worked in industries like Banking and Finance, Manufacturing, and Information Technology (IT).

Which business areas has Wolfram worked in recently?

Wolfram has recently worked in business areas like Information Technology (IT), Product Development, and Quality Assurance (QA).

What is Wolfram's education?

Wolfram holds a Master in Political Science from University of Münster.

Does Wolfram have any certificates?

Wolfram has 4 certificates. Among them, these include: Linux Professional Institute: Level 1 Certification, Sun Certified Enterprise Component Developer, and Sun Certified Java Programmer.

What is the availability of Wolfram?

Wolfram is immediately available full-time for suitable projects.

What is the rate of Wolfram?

Wolfram's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.