Rafael Kolloch-Senior Android Developer / Team-Lead
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Experience
Senior Android Developer / Team-Lead
IBM Deutschland
- Further development and release support of a white-label e-prescription component for health insurance companies
- Technologies: Android (Kotlin), Kotlin Multiplatform, Coroutines, Jetpack Compose, MVVM, StateFlow, Gradle, ProGuard
Android Developer
ZGS Bildungs-GmbH (Deutsche Schülerhilfe)
- Concept, architecture, development and deployment of the new online tutoring app for Deutsche Schülerhilfe
- Technologies: Android (Kotlin), AndroidX, Android Jetpack, MVVM, LiveData, Room (SQLite), Retrofit, Gson, Firebase, push notifications, Zendesk, Gradle, ProGuard
Full-stack Developer
Selbstständig
- Development and maintenance of the research platform for stock investors "Trader Radar"
- Technologies: Android (Kotlin), AndroidX, Android Jetpack, MVVM, LiveData, Room (SQLite), Retrofit, Gson, Firebase (Cloud Messaging, Crashlytics, Remote Config), in-app purchases, AdMob, Gradle, ProGuard, PHP, MySQL, HTML, CSS, JavaScript
Lead Developer
Deutsche Bank
- Lead development of a prototype and the subsequent design, deployment, and ongoing enhancement of a mobile payment app
- Accompanying security audits and hardening
- Technologies: Android (Kotlin), AndroidX, Android Jetpack, Room (SQLite+SQLCipher), Retrofit, Gson, Bluetooth, NFC, native communication with card terminals, encrypted databases and communication, Gradle, ProGuard, JUnit, Robolectric, Mockito, MockK
Lead Developer
Leading German construction machinery provider
- Lead development of a trade fair companion app
- Technologies: Android (Java/Kotlin), AndroidX, Android Jetpack, Swagger CodeGen, encrypted databases and communication, Gradle, ProGuard, JUnit, Robolectric, Mockito, MockK
Full-stack Developer
Self-Employed
- Full-stack development of the math games app "Crystal Math"
- Technologies: Android (Java), Google Standard Frameworks, SQLite, Retrofit, Firebase (Cloud Messaging, Real Time Database, Remote Config, Crashlytics), Facebook SDK, Gradle, ProGuard, PHP, MySQL
Lead Developer
Leading German logistics company
- Designing, deploying and continuously improving a comprehensive mobile app
- Performing security audits and hardening
- Technologies: Android (Java), Google Standard Frameworks, Dagger2, SQLite, Retrofit, Swagger CodeGen, database and communication encryption, Gradle, ProGuard
Android Developer
Leading German automotive supplier
- Development of a companion app for light e-mobility vehicles
- Technologies: Android (Java), Bluetooth LE, database and communication encryption
Android Developer
Swiss Bank
- Development of a mobile banking app in close collaboration with the client's team
- Technologies: Android (Java), Android-JavaScript bridge, communication encryption
Industry experience
See where this freelancer has spent most of their professional time.
Experienced in Education, Banking and Finance, Information Technology, Healthcare, Insurance, and Transportation.
Business area experience
See which departments and functions this freelancer has contributed to most.
Experienced in Information Technology and Product Development.
Skills
- Activity Areas: Architecture, Consulting, Development, Feasibility Analysis
- Programming Languages: Kotlin, Java, Objective-C, Swift, Php
- Ides: Android Studio, Intellij Idea, Xcode, Eclipse, Netbeans, Visual Studio Code
- Industries: Automotive, Banking, Logistics, Lottery, Public Sector, Retail, Utilities, Insurance
- Android: Android Sdk, Kotlin Multiplatform, Jetpack Compose, Koin, Dagger2, Coroutines, Mvvm, Mvp, Mvi, Room, Livedata, Sqlite, Sqlcipher, Retrofit, Okhttp, Gson, Firebase (Ads, Cloud Messaging, Crashlytics, Realtime Database, Remote Config), Admob, Glide, Picasso, Timber, Material Design Ui, Biometric Authentication (Fingerprint), Gradle, Unit Tests, Junit, Mockito, Mockk, Robolectric, Release Management
- Ios: Afnetworking, Cocoapods, Cocoalumberjack, Firebase (Ads, Crashlytics, Cloud Messaging), Release Management
- Misc: Regular Expressions, Reverse Engineering, Pentesting, Web Scraping
- Project Management / Ci: Scrum, Atlassian Toolchain, Jira Administration/Customization, Bitbucket, Jenkins, Teamcity, Sonarqube
- Databases: Sqlite (With Sqlcipher), Mysql, Oracle, Db2, Postgresql
- Platforms: Windows, Linux/Unix, Macos
- General It Skills: Common Office Suites Like Ms Office And Open Office, Experience With Graphics Editing Tools Like Photoshop, Gimp
Languages
Education
TU Dortmund
Diploma · Computer Science · Dortmund, Germany
FernUniversität in Hagen
Part-time distance learning · Computer Science · Hagen, Germany
Training as an IT Specialist (Application Development)
Vocational Training · IT Specialist (Application Development) · Dortmund, Germany
Statistics
Experience
Expertise
Qualifications
Profile
Frequently asked questions
Have questions? Find more information here.
Rafael is based in Dortmund, Germany and can operate in on-site, hybrid, and remote work models.
Rafael speaks the following languages: German (Native), English (Advanced), Polish (Advanced), Spanish (Elementary).
Rafael has at least 12 years of experience. During this time, Rafael has worked in at least 4 different roles and for 9 different companies. The average length of individual experience is 1 year and 3 months. Note that Rafael may not have shared all experience and actually has more experience.
Based on recent experience, Rafael would be well-suited for roles such as: Senior Android Developer / Team-Lead, Android Developer, Full-stack Developer.
Rafael's most recent position is Senior Android Developer / Team-Lead at IBM Deutschland.
In recent years, Rafael has worked for IBM Deutschland, Selbstständig, and Self-Employed.
Rafael is most experienced in industries like Education, Information Technology, and Banking and Finance. Rafael also has some experience in Healthcare, Insurance, and Transportation.
Rafael is most experienced in business areas like Information Technology and Product Development.
Rafael has recently worked in industries like Education, Information Technology, and Banking and Finance.
Rafael has recently worked in business areas like Information Technology and Product Development.
Rafael holds a Master in Computer Science from TU Dortmund.
The availability of Rafael needs to be confirmed.
Daily rate distribution
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Average rates for similar positions
Rates are based on recent contracts and do not include FRATCH margin.
The average daily rate is the mean of all daily rates from recent contracts of comparable freelancers on our platform.
The median daily rate is the middle value of all daily rates — half of comparable freelancers charge less, half charge more. Unlike the average, it is barely affected by outliers.
Calculated based on our freelancers’ daily rates as of 26 Aug 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
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