Kotlin Experts in Berlin
in minutes with the power of AIWork with specialists who build modern Android applications, resilient server-side microservices with Ktor and Spring Boot, and cross-platform logic using Kotlin Multiplatform. FRATCH matches you with vetted, available freelance professionals in minutes.
Meet FRATCH Experts in Berlin, who have recently used Kotlin
Rüdiger S.
Last position:
Full-Stack Software Engineer / Consultant for Digitalization at ARTEVENT
Designed, built, and launched an internal event planning web application used by over 100 department leads for a large event, despite having no dedicated testing phase.
Ensured smooth, failure-free operation during first production use, leading to the tool being adopted for future events.
Automated catering calculations and related workflows, significantly reducing email communication and manual computation effort for meal planning.
Managed deployment and hosting on a Linux server using Coolify, including application setup and runtime operations.
Hired and guided a communication designer on UX while independently owning all technical decisions and implementation.
Marvin M.
Last position:
Co-founder & CTO · Freelance Software Engineer (AI & SaaS) at Self-employed
- Self-employed · Berlin, Germany
- Co-founded the company and own the entire technical side: product architecture, backend, frontend, infrastructure and operations.
- Designed and built the Automated Booking System (ABS) as well as the core platform and payment logic.
- Development of AI-powered SaaS products, from architecture through backend and frontend to production operation.
- Technical consulting on product architecture, data protection and permissible automation.
- Building, running and monetising my own API products for AI agents, each available as a REST interface and as an MCP server.
- Full ownership of architecture, infrastructure, billing, legal texts and go-to-market.
Santhosh K.
Last position:
Freelance Software Engineer at Zalando SE
- Drive migration of enterprise authorization platform from Styra DAS to open-source OPA via Skipper (Zalando's Golang-based ingress proxy) integration
- Optimise k8s resources and integrate native Prometheus metrics with OPA
- Migrate from internal monitoring solution to Prometheus CRs + Dash0
Tech Stack: Java/Kotlin, Golang, Python, Spring Boot, AWS, Kubernetes, Docker, OpenTofu, Prometheus, Grafana
Matthias Z.
Last position:
Senior Flutter Developer at Materna
- Developed a Flutter app for eID ID card logins
- Focus: Flutter, iOS, eID, AusweisAppSDK, Mason, Keycloak, Agentic Coding, Arc42, Jenkins
Maciej R.
Last position:
Full Stack Developer (Freelancer) at Runbuggy
- Led development of RunBot AI assistant autonomously using LLM-powered workflow automation (React, TypeScript, Java, MongoDB, NATS)
- Architected TMS platform providing unified transportation management and real-time logistics visibility with AI processing pipelines
- Designed event-driven microservices architecture supporting marketplace
- Drove architectural decisions and technical leadership across full-stack platform development
Imran A.
Last position:
Software Engineer II at LivePerson Germany GmbH
- Led development of 15+ microservices (Java 17, Spring Boot) driving customer interactions; migrated from on-prem to GCP Kubernetes, improving scalability and reducing infra cost by 20%.
- Optimized user services with CouchDB caching and API refactoring, cutting response times by 35% and enhancing customer experience.
- Implemented canary deployments, FluxCD GitOps, and CI/CD optimizations in GitLab, reducing release lead time by 25% and enabling zero-downtime rollouts.
- Set up Grafana health checks and Anodot alerts for latency, error, and throughput monitoring, reducing MTTR by 40%.
- Built secure APIs using OAuth2, DPoP, and Gatekeeper, integrated REST and GraphQL, and achieved 90%+ test coverage with unit and E2E tests.
- Mentored junior developers, promoted Agile best practices, and collaborated cross-functionally to deliver high-impact, reliable customer-facing features.
Ben S.
Last position:
AI Trainer & Data Annotator at Scale AI
- RLHF & Model Evaluation: Evaluated, ranked, and refined Large Language Model (LLM) responses based on accuracy, reasoning quality, safety guidelines, and factual correctness.
- Data Annotation & Prompt Engineering: Created high-complexity prompts, edge-case scenarios, and gold-standard reference answers to train and fine-tune generative AI models.
- Quality Assurance & Verification: Conducted rigorous fact-checking, logical consistency validation, and multi-turn response optimization.
Mohsin H.
Last position:
BBM GenAI MiDAS program coordinator for Bosch eBike at Robert Bosch GmbH
The MiDAS program aims to integrate Generative AI across the entire BBM organization. My role is to enable the eBike division to adopt and leverage Generative AI by collaborating closely with the MiDAS team in India.
Management:
- Enable the eBike division to adopt GenAI through tailored solutions.
- Collaborate with the MiDAS team in India to design solutions for Generative AI use cases specific to the eBike division.
- Coordinate with the eBike teams to integrate GenAI systems, tools, plugins, and services provided by the MiDAS team.
- Plan roadmaps with eBike and MiDAS India team Product Managers for the delivery and integration of Generative AI solutions.
Ibrahim H.
Last position:
Senior Full Stack / AI Engineer at Punktum Digital GmbH
- Context: Healthcare and laboratory teams required faster document analysis, treatment-planning support, and reliable AI workflows for MR/VR-assisted operations.
- Contribution: Built the AI healthcare platform, model/agent workflows, VR-glasses deployment platform, REST APIs, Next.js/React interfaces, and CI/CD pipelines.
- Impact: Delivered a production-ready AI product foundation that improved clinical document review, supported laboratory automation, and made VR fleet deployment manageable across environments.
Tech: TypeScript, Next.js, Node.js, React, Java, Spring Boot, Python, PyTorch, TensorFlow, Docker, PostgreSQL, OpenAPI, GitLab, GitHub Actions.
Can K.
Last position:
DevOps Specialist at Eviden Germany GmbH
Manage the development release and update process for a digitized nationwide trade register project "AuRegis".
Support software in Kubernetes/OpenShift environments, configure management with Kustomize, and implement CI/CD pipelines using Jenkins/GitLab, SonarQube, ArgoCD, and Azure.
Oversee system release of microservice architecture.
Build the CI/CD stack from scratch with GitLab CI, integrating integration tests, dependency checks, and security measures.
Automate deployment onto OpenShift using Kustomize.
Set up infrastructure components for development, code review, and code quality analysis including SonarQube.
Integrate GitOps tools such as Kustomize and ArgoCD, using both Azure and private cloud for sensitive data handling.
Develop Python scripts in Jenkins for cryptostore configuration and system packaging of products and microservices into deployable units.
Automate delivery to customers and deployment on test systems.
Create Kustomize manifests for microservices and develop the related automation, treating documentation as code for clarity and reproducibility.
Serve as technical advisor for the project's first go-live and oversee further deployments as technical rollout manager.
Toralf C.
Last position:
IT Consultant in PKI Software Development at BWI
- Implementation of a full-stack application with Angular as the frontend framework and Java as the backend language
- Use of the Swagger OpenAPI specification for REST communication between the frontend and backend applications
- Control of a card printer via the Nexus Card SDK framework
- Design and implementation of card management software with a web interface and a JavaFX module for printer monitoring
- Use of Cucumber tests for test automation and creation of test artifacts to test outside the development environment
- Use of Wireshark for network investigations to analyze the API of a third-party product and to monitor the REST API of the self-developed software
Nikunjkumar P.
Last position:
Senior Java Backend Developer at Questax Professionals GmbH
- Provide the Price Listing Service team with prices for all cars and vans in different markets
- Adapt market-specific requirements such as taxes, government subsidies, campaigns
- Import and synchronize new prices for all new and existing cars and store them in the Redis datastore
- Support our product and on-call duty
- Daily business, development of new features, bug fixing
- Pair programming, code review, mob programming
- Develop POCs for new ideas
- Maintain and extend the backend
- DevOps tasks
- Run Kubernetes updates
- Adjust and further develop Kubernetes resources
- Develop and adapt Helm charts
- Adapt and update ArgoCD
- Maintain, adapt, and improve CI/CD
Cristian P.
Last position:
iOS-Teamleiter at Qlaunch Gmbh
- Contributed to the architecture design process, leading to scalable and maintainable solutions for complex projects
- Improved app performance through code optimization and implementation of efficient algorithms
- Led a team of iOS developers to complete projects on time and achieve customer satisfaction
- Implemented core design plans into complete iOS app frameworks and delegated project components to corresponding team members
- Key project: City Guide ([link]
Ursula R.
Last position:
Sabbatical with Training at Own Sabbatical
Mario J.
Last position:
Architect / Developer at handyhase
- Overhaul of the entire design and implementation of new UI/UX aspects using React
- Planning of the software architecture and structuring of the project for long-term scalability using Git for version control
Discover over 15,000 top freelancers
Statistics of experts using Kotlin
Aggregated from the professional profiles of matched freelancers.
Experience
17 years
Position duration
2.2 years (Germany: 2.7 years)
Positions per freelancer
11 (Germany: 12)
Top business areas
Information Technology, Product Development, Project Management
Top industries
Information Technology, Retail, Media and Entertainment
Certification focus areas
Information Technology, Product Development, Project Management
Bachelor's degree or higher
95% (Germany: 93%)
Master's degree or higher
54% (Germany: 56%)
Doctorate
8% (Germany: 9%)
Certifications per freelancer
1 (Germany: 2)
Most common languages
English, German, French
Speak two or more languages
98%
Based on our profile pool as of 9 Oct 2026.
Daily rate distribution
The chart shows how the daily rates of experts in this technology in Berlin are distributed, based on recent contracts on our platform. Each bar covers a rate range — its height shows the share of experts charging within that range.
Average rates of experts in Berlin using Kotlin
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 9 Oct 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
Kotlin experts industry focus
See which industries our matched freelancers work in most often — every figure is calculated live from the freelancers on FRATCH.
- Information Technology (96%)
- Retail (44%)
- Media and Entertainment (40%)
- Healthcare (38%)
- Automotive (36%)
- Banking and Finance (33%)
- Education (29%)
- Transportation (27%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
Modern Multiplatform and Server Architecture
Kotlin is a modern, statically typed language running on the Java Virtual Machine and native environments. Engineering teams across Berlin utilize it to construct reactive backends, reliable event-driven pipelines, and native mobile software. Full interoperability with Java allows legacy codebases to adopt modern paradigms incrementally without complete rewrites.
Native Android and Multiplatform Capabilities
As the preferred foundation for Android runtime software, the language delivers declarative interfaces with Jetpack Compose. Beyond mobile, Kotlin Multiplatform enables teams to share networking, data storage, and business logic across iOS and desktop targets while preserving native presentation layers.
Server-Side Frameworks and Concurrency
For distributed backend services, specialists deploy lightweight frameworks such as Ktor alongside Spring Boot and Micronaut. Built-in language features eliminate entire classes of runtime failures while simplifying asynchronous execution paths:
- Null safety to eliminate null pointer exceptions entirely
- Kotlin Coroutines for structured, non-blocking concurrency
- Asynchronous data streaming through reactive Kotlin Flows
- Type-safe builders and domain-specific languages for clean configurations
Berlin Ecosystem and Industry Applications
Berlin's tech ecosystem relies on the language across consumer fintech platforms, mobility services, and enterprise software products. Local teams frequently combine JVM performance with rapid delivery cycles, creating demand for professionals who handle cloud-native deployments and containerized services in fast-paced product environments.
When Organizations Hire External Expertise
Companies bring in dedicated freelance specialists when migrating legacy Java microservices, launching greenfield mobile applications, or introducing cross-platform libraries. External talent speeds up complex refactoring, establishes automated testing suites with MockK and Kotest, and guides architecture decisions without lengthy onboarding cycles.
Hallmarks of Senior Engineering Talent
Exceptional specialists master structured concurrency, understand low-level bytecode output, and optimize memory allocations. They design clear API contracts, maintain high test coverage, and integrate continuous delivery pipelines while collaborating effectively across distributed and bilingual engineering environments.
Frequently asked questions
Key details about Kotlin, drawn from the questions we get asked most.
Organizations adopt Kotlin primarily for native Android applications and modern server-side backend systems. It is also an outstanding choice for Kotlin Multiplatform projects that share business logic between iOS and Android, as well as microservices built on frameworks like Ktor or Spring Boot.
While running on the same runtime, Kotlin dramatically reduces boilerplate code through data classes, smart casts, and built-in null safety. Its native support for coroutines allows backend services to handle thousands of concurrent requests with significantly lower memory overhead than standard thread-per-request Java models.
A proficient Kotlin professional typically brings deep familiarity with the Java ecosystem, Gradle build configurations, and containerization with Docker. Depending on the focus area, they should also demonstrate mastery of Jetpack Compose for client-side interfaces or cloud-native orchestration tools for backend deployments.
Yes, Kotlin is fully interoperable with Java, allowing both languages to coexist within the same repository and build pipeline. Teams can call existing Java libraries directly without wrappers and migrate individual classes or modules incrementally without disrupting production systems.
Look for hands-on experience in production environments, particularly how the candidate manages structured concurrency with Kotlin coroutines and reactive flows. High-quality professionals write idiomatic code without treating the language like Java, design modular architectures, and maintain rigorous test suites using tools like Kotest and MockK.
Most Kotlin professionals based in Berlin work through flexible remote setups while remaining open to periodic on-site sprint planning or architectural workshops. Berlin's international startup hub means these specialists collaborate smoothly in English and integrate seamlessly into cross-functional distributed squads.
Yes, Kotlin Multiplatform is stable and widely adopted by modern product companies to share domain logic, data models, and networking clients across platforms. Freelance specialists frequently implement it to accelerate roadmap delivery across web, iOS, and Android without duplicating core engineering efforts.
Migrating critical enterprise services requires a senior Kotlin expert who understands bytecode interop, memory profiling, and automated migration tooling. Experienced specialists design clear boundary interfaces and establish comprehensive test coverage so migration proceeds incrementally without downtime or regression bugs.
The average hourly rate of freelancers in Berlin, Germany who have used Kotlin in their recent projects is 97 €, which corresponds to a daily rate of about 777 € based on an 8-hour working day.
Of the freelancers in Berlin, Germany who have used Kotlin in their recent projects, 95% hold at least a Bachelor's degree, 54% hold at least a Master's degree, and 8% hold a doctorate.
On average, freelancers in Berlin, Germany who have used Kotlin in their recent projects have 17 years of professional experience, with a single engagement typically lasting around 2.2 years.
The most common languages among freelancers in Berlin, Germany who have used Kotlin in their recent projects are English (98%), German (96%), and French (13%).
The most common industries among freelancers in Berlin, Germany who have used Kotlin in their recent projects are Information Technology (96%), Retail (44%), and Media and Entertainment (40%).
The most common business areas among freelancers in Berlin, Germany who have used Kotlin in their recent projects are Information Technology (98%), Product Development (93%), and Project Management (53%).
Main locations of FRATCH Experts, who have recently used Kotlin
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 
Hamburg 
Munich 
Cologne 
Frankfurt 
Dusseldorf Countries:
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