RxJava Experts in Germany
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Meet FRATCH Experts in Germany, who have recently used RxJava
Ola Van Dunen
Last position:
IT Lecturer
- IT training in theory and practice for IT specialists in application development and system integration
Ayhan Gezer
Last position:
Senior QA Engineer / Test Automation Engineer / SDET at Rewe digital
Consulting, designing, and implementing the software testing lifecycle for multiple Android apps and backends Introducing test automation with Appium, SpringBootTest, RestAssured Setting up and managing emulators Developing an E2E library, an integration library, a Testcontainers library, and other libraries Developing, implementing, and advising on CI strategies Building the test environment with Testcontainers and virtualization Developing and implementing test cases for integration tests and end-to-end tests Establishing a maintainable test architecture with low entry barriers to simplify the creation of automated tests Some tools and technologies used: JUnit, RestAssured, Testcontainers, Kubedock, Appium, Android emulator, Jira Xray, Mockito, WireMock, Spring Framework, Kotlin
Shubhangi Patil
Last position:
Parental leave
- Technology update
- Microsoft Azure certification
Yodgorbek Komilov
Last position:
Android Developer at Mein Artz
- Led the development of a doctor scheduling Android app, integrating Jetpack Compose and Kotlin Multiplatform, achieving a 30% performance improvement.
- Implemented complex UI components, ensuring 99.8% crash-free user sessions.
- Seamlessly integrated Compose UI with existing View-based components.
- Optimized API calls, reducing load times by 20%.
- Tech Stack: Kotlin, Jetpack Compose, KMM, MVVM, Koin, Firebase, Stripe API, Crashlytics
Jan G.
Last position:
Master Data Application at confidential
Visualization, search, and maintenance of various types of master data, providing them via a REST API, and implementing a variety of import and export formats.
Implementation, architecture, project management.
Technologies and tools: Angular (Signals, Signal Store, swagger-codegen, standalone components), Java, PostgreSQL, ActiveMQ, JavaScript, Spring Boot (Spring Core, Spring MVC, Spring Data/JPA via Hibernate, Spring Security, Spring Modulith), JUnit, Flyway, QueryDSL, GraphQL, REST API, Node, npm, Maven, SonarQube, GitLab CI/CD pipelines, Docker, Nexus, OpenAPI + Swagger UI, Keycloak, OAuth2, OpenID Connect, IntelliJ IDEA, Jira, Confluence.
Khaled Mohamed
Last position:
Senior/Staff Backend Engineer at Heycar (Mobility Trader GmbH)
- Heycar is a leading automotive platform redefining the used car market through intelligent data pipelines, multi-tenant services, and dealer-focused tooling. I led initiatives across backend architecture, data ingestion, and identity management to enhance scalability, reliability, and developer productivity.
- Ingestion Platform: Designed a unified ingestion platform with YAML-based configuration, enabling new dealer data pipelines to be onboarded without code changes, cutting setup time from ~2 months to 2-3 days and improving scalability by 40%.
- Keycloak Leadership: Acted as the company's Keycloak expert, scaling it for multi-tenant identity management and extending functionality with custom plugins and delegated admin APIs.
- Back-Office Tooling: Developed a back-office application integrated with Salesforce, enabling dealers to manage inventory, convert leads, and handle support requests in real time.
- Multi-Tenant Migration: Collaborated across backend teams to migrate Heycar's core services into a unified multi-tenant cluster, ensuring high availability.
- Frontend CI Optimization: Optimized monorepo delivery by implementing CircleCI dynamic config with NX, deploying only affected UI projects and drastically cutting build times.
- Observability & Mentorship: Enhanced monitoring and release reliability while mentoring backend engineers and improving code review standards.
Md. Shah Samir
Last position:
Android Engineer at ScrapBays Ltd.
- Built features using Jetpack Compose
- Improved location-based features with in-memory caching
- Developed Merchant-to-Merchant chat functionality from scratch
- Integrated FCM with deep links to enable contextual push notifications
- Performance tuning for Google Maps view using clustering for better performance in dense areas
Mathias Vogler
Last position:
Senior Android Developer / Freelancer at Adevinta
- Further development of the classifieds app
- Android
- Kotlin
- Coroutines
- Jetpack Compose
Janusz Mazurek
Last position:
IoT Edge Computing / Self-Driving-Cars at Automotive consulting company
- Platform: Python ecosystem, RHEL 8, K10, AWS IoT Core, AWS Lambda, MLOps
- Software: Java JEE/cloud, IntelliJ IDEA, AWS IoT Core, AWS Edge and Lambda, AWS SageMaker SDK, Docker Compose, Kubernetes, OpenShift 4, Tekton, Flux, Helm charts, JSON/XML technology, Nginx, Apache Spark, OpenAI (GPT Plus, DALL-E 3, Whisper), GAN, GitHub Copilot, AI/machine and deep learning, Jupyter notebooks, TensorFlow 2, Colab, Keras API, Prometheus, Grafana, Conda, Python 3.9, PySci stack (NumPy, pandas, Scikit-learn, matplotlib)
- Responsible for webinar:
- IoT edge computing: architecture, components, resources, management
- IoT edge computing with MicroK8s, designing and creating flows/diagrams for AWS, three-step model for IoT ecosystem
- IoT processes, connectivity, data transfer and deployment, security
- Optimization of edge computing for IoT networks and services (AWS SQS queue, SNS notifications, events, analytics, buttons, device management/defender, Things Graph)
- Machine/deep learning frameworks (models, training, pipeline optimization, deployment in the cloud/at the edge (OpenShift), monitoring workloads with Prometheus and Grafana)
- Performance optimization for low latency/resilience using adaptive ML/DL/RL models for customer IoT data
- Analysis of large sensor data sets with Apache Spark, Kafka clusters
- Kasten K10 data management platform on Kubernetes multi-cluster with Helm chart, deployment, backup/disaster recovery (RTO/RPO), data lifecycle and security management
- Implementation of multilayer artificial neural network (ANN) with TensorFlow 2 and Colab for regression and classification; data analysis and provisioning for applications; development of models for testing and training, deployment of models
- Automation of business streamline processes with AI (Azure OpenAI, Discord bots/Zapier apps AI assistants (IntelliJ, GitHub Copilot))
Mario Ellebrecht
Last position:
Developer and Consultant at Freelancer
Johannes Lauber
Last position:
Android Developer at Adevinta
- Implementing tasks for the Privacy and Trust and Safety team
- Technologies: Kotlin Coroutines, Jetpack Compose, RxJava, Kotlin Room, Dagger, Epoxy, Google Pay
Discover over 15,000 top freelancers
Statistics of experts using RxJava
Aggregated from the professional profiles of matched freelancers.
Experience
17 years
Position duration
1.9 years
Positions per freelancer
14
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Automotive, Healthcare
Certification focus areas
Information Technology, Product Development, Business Intelligence
Bachelor's degree or higher
100%
Master's degree or higher
57%
Certifications per freelancer
1
Most common languages
German, English, French
Speak two or more languages
100%
Based on our profile pool as of 30 Aug 2026.
Daily rate distribution
The chart shows how the daily rates of freelancers in this technology in Germany are distributed, based on recent contracts on our platform. Each bar covers a rate range — its height shows how many freelancers charge within that range.
Average rates of experts in Germany using RxJava
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 30 Aug 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
About the technology
Reactive flow
RxJava is a library for composing asynchronous work as streams. It helps teams model data, events, and background tasks in a way that is easier to chain, transform, and cancel. Companies use it for mobile apps, API clients, message processing, and service orchestration.
Common use cases
- Android screens that react to user input and live data
- API calls that need retries, mapping, or timeouts
- Event pipelines with clear transformation steps
- Background work that must not block the main thread
- Integration layers for legacy and modern services
Ecosystem
RxJava sits inside the larger ReactiveX family and is often paired with Retrofit, OkHttp, Room, and Kotlin coroutines where they fit the stack. Strong professionals know schedulers, operators, subjects, error handling, and how to keep chains readable. They also understand when a simple callback or coroutine is the better choice.
When to bring help
Teams bring in freelance specialists when an RxJava flow is hard to debug, when threading bugs appear, or when old reactive code needs cleanup. This is common in Germany-based product teams that maintain Android apps, connected platforms, and internal tools with strict stability goals. A good expert can untangle chains without breaking behavior.
What good work looks like
Strong RxJava professionals write small, testable streams and keep side effects under control. They handle cancellation, backpressure, and error paths with care. They also leave code that other specialists can read, extend, and migrate later.
Choosing the right specialist
Look for experience with production RxJava code, not just toy examples. Ask how they debug race conditions, how they test reactive flows, and how they reduce operator complexity. The best specialists can explain tradeoffs clearly and make older reactive code easier to maintain.
Frequently asked questions
Before you brief your next project: the most common questions about RxJava.
RxJava is used to model asynchronous work as streams. That makes it useful for Android screens, API chains, event handling, and background tasks that need clear sequencing. It is especially helpful when several steps must be combined, retried, or cancelled cleanly.
RxJava and coroutines both handle asynchronous work, but they do it differently. RxJava is stronger when a codebase already uses reactive chains, rich operators, or cross-platform ReactiveX patterns. Coroutines are often simpler for new work, so a good specialist knows when to keep RxJava and when to migrate part of the flow.
A company usually brings in a RxJava specialist when reactive code has become hard to debug or maintain. Common triggers are threading issues, confusing operator chains, and legacy Android code that still depends on reactive streams. A freelancer can stabilize the code and improve the design without a full rewrite.
A strong RxJava professional usually also knows Android architecture, Java or Kotlin, testing, threading, and HTTP clients such as Retrofit. Familiarity with Room, OkHttp, and logging tools helps too. Those skills make it easier to trace data flow from the UI down to the network or database.
RxJava can still be a good choice, but only when it fits the team and the codebase. It is often a strong option for systems that already use reactive patterns or depend on its operator set. For a greenfield project, many teams compare it with coroutines or other simpler async tools first.
Yes, RxJava work is often done remotely because most tasks are code, tests, and debugging. For teams in Germany, remote collaboration is common, especially when the specialist can join sprint reviews and explain reactive flows clearly. On-site time can still help when a system is tightly coupled to local teams or legacy mobile releases.
A strong RxJava specialist writes code that is easy to follow, test, and change. Look for clear handling of errors, cancellation, and schedulers, plus a calm explanation of why a stream is built a certain way. Good work reduces complexity instead of adding more operators.
A serious RxJava freelancer will ask where the streams begin, where they end, and which parts are hardest to test. They should also ask about threading rules, existing operator patterns, and whether the goal is cleanup, feature work, or migration. Those questions help them avoid breaking production behavior.
The average hourly rate of freelancers in Germany who have used RxJava in their recent projects is 82 €, which corresponds to a daily rate of about 655 € based on an 8-hour working day.
Of the freelancers in Germany who have used RxJava in their recent projects, 100% hold at least a Bachelor's degree and 57% hold at least a Master's degree.
On average, freelancers in Germany who have used RxJava in their recent projects have 17 years of professional experience, with a single engagement typically lasting around 1.9 years.
The most common languages among freelancers in Germany who have used RxJava in their recent projects are German (100%), English (100%), and French (18%).
The most common industries among freelancers in Germany who have used RxJava in their recent projects are Information Technology (100%), Automotive (64%), and Healthcare (55%).
The most common business areas among freelancers in Germany who have used RxJava in their recent projects are Information Technology (100%), Product Development (100%), and Quality Assurance (45%).
Main locations of FRATCH Experts, who have recently used RxJava
Our freelancers and interim experts are at home across the DACH region — available on-site in the major business hubs or fully remote. Choose a location to discover matched specialists, local market insights and up-to-date availability.
Berlin Hamburg Munich Cologne Frankfurt Stuttgart Dusseldorf Leipzig Dortmund Essen Bremen Dresden Hanover Nuremberg Request a free demo
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FRATCH CEO
