Kotlin Experts in Berlin
in minutes from over 15,000 CVs with AI-powered matchingHire experts who build Android apps, backend services on the JVM, and Kotlin Multiplatform products. They handle clean code, testing, migration work, and modern mobile stacks, with fast, precise matching to vetted, available freelancers.
Meet FRATCH Experts in Berlin, who have recently used Kotlin
Rüdiger Schulz
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.
Santhosh Kannan
Last position:
Freelance Software Engineer at Zalando SE
- Support Authorization as a Service initiative for enterprise-scale authorization platform
- Incorporate comprehensive observability solutions into authorization infrastructure
- Provision and manage AWS infrastructure for authorization services
- Mentor development team on AWS and Kubernetes best practices
- Tech Stack: Java/Kotlin, Golang, Python, OPA, Spring Boot, AWS, Kubernetes, Terraform, ELK Stack, Prometheus, Grafana
Maciej Rosiek
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 Ali
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.
Viktor Shcherban
Last position:
AI Engineer (Freelance) at Empion
Enterprise AI content categorization and AI-powered web research.
- Built multi-LLM evaluation framework with annotated data
- Iterated LLM error rates based on annotated datasets
- Implemented AI-powered web research pipeline Stack: LLM, evals, OpenRouter, Python, Node.js, TypeScript, React
Abhiroop Basu
Last position:
Software Engineer III at Foundry Digital
- Developed and deployed microservices in Kotlin and Spring Boot, integrated AWS Secrets Manager to secure credentials and decreased network calls using Spring cache.
- Refactored Kafka consumer using Spring Kafka with semaphore-based backpressure to cap records and keep heap memory stable under spikes; switched to batch upserts to cut down on database invocations; added Testcontainers integration tests for Kafka and database to pave the way for future changes.
- Automated the financial reconciliation workflow in Spring Boot (Kotlin) using Spring Scheduler, transactional boundaries, JPA/Hibernate on MySQL, and Flyway migrations, saving the accounts team 16+ hours per week.
- Designed and dockerized payments end-to-end test framework in Robot (Python) with reusable keyword libraries and profiles; integrated with GitLab CI (JaCoCo XML and HTML reports) to accelerate releases and lift code coverage to 80%.
- Implemented end-to-end observability on Datadog by instrumenting services with Datadog APM, correlating metrics and logs, provisioning dashboards, and creating monitors with burn-rate alerts and anomalies to harden reliability and give stakeholders clear visibility.
Cristian Petra
Last position:
iOS Team Lead at Qlaunch Gmbh
- Contributed to the architecture design process, resulting in scalable and maintainable solutions for complex projects.
- Enhanced app performance by optimizing code and implementing efficient algorithms.
- Stayed current with industry trends to ensure implementation of best practices in app development.
- Led a team of iOS developers for timely completion of projects and achieving client satisfaction.
- Translated basic design plans into full iOS app frameworks, delegating project components to appropriate team members.
- Estimated work hours and tracked progress using Scrum methodology.
Daniel Martinez Maqueda
Last position:
Founding Database Engineer at tonbo.io
Working on the next iteration of tonbo to make it the most flexible in-process analytical database in the market that scales and is operated with strong availability
Introduced object scope cache to the remote storage layer to avoid I/O churn
Working on refactoring WAL to support remote storage
Taking care of the health of the systems as well as designing the operational story and bringing them to production
Technologies: LSM, WAL, Arrow, Parquet, Rust
Ibrahim Hilali
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 Kocyigit
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.
Craft the CI/CD stack from scratch with GitLab CI, integrating integration tests, dependency checks, and security measures.
Automate deployment onto OpenShift using Kustomize.
Establish infrastructure components for development, code review, and code quality analysis including SonarQube.
Integrate GitOps tools such as Kustomize and ArgoCD, leveraging 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.
Craft Kustomize manifests for microservices and develop accompanying 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.
Ursula Raab
Last position:
Sabbatical with Training at Own Sabbatical
Mario Jelinski
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
Daniel Suszczynski
Last position:
Engineering Leader & AI-Assisted Developer at Independent · Building with AI
- Building a full-stack e-commerce product using AI-assisted development, deliberately returning to hands-on engineering to validate how AI changes software development workflows and team dynamics.
- Exploring VP Technology, Head of Engineering, and Director of Engineering opportunities where hands-on AI experience meets organisational scaling expertise.
- Open to advisory conversations on AI-augmented engineering teams, technology strategy, platform architecture, and organizational design.
- No registered business. No commercial activity.
Igor Kazarnovskiy
Last position:
Freelance Software Developer
Christian Golecki
Last position:
Product Owner – Redesign of an iOS and Android SaaS application platform at iApps Technologies GmbH
- Led the redesign of an iOS and Android B2B SaaS solution.
- Developed the product vision and strategy and designed the platform architecture.
- Worked closely with cross-functional teams to create a user-centered, forward-looking product.
- Identified market trends and analyzed feedback from stakeholders and customers.
- Developed a well-thought-out feature set.
- Led the product design and development process.
- Created Balsamiq wireframes.
- Conducted comprehensive market and competitor analysis.
- Defined the product roadmap and feature scope, managed and prioritized the backlog.
- Crafted and wrote epics and user stories.
- Briefed UI designers and reviewed and approved Figma layouts.
Discover over 15,000 top freelancers
Statistics of experts using Kotlin
Aggregated from the professional profiles of matched freelancers.
Experience
18 years (Germany: 17 years)
Position duration
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
97% (Germany: 93%)
Master's degree or higher
59% (Germany: 57%)
Doctorate
9% (Germany: 10%)
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 30 Aug 2026.
Daily rate distribution
The chart shows how the daily rates of freelancers in this technology in Berlin 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 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 30 Aug 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
About the technology
Kotlin at a glance
Kotlin is a modern language for JVM, Android, server-side work, and shared code across platforms. It is known for concise syntax, null safety, and good tooling in IntelliJ IDEA and Android Studio. Companies use it to ship app features, backend services, and reusable libraries.
What teams build
- Android app features and app refactors
- JVM services, APIs, and batch jobs
- Shared logic with Kotlin Multiplatform
- Clean modules, libraries, and build scripts
Kotlin fits product teams that want less boilerplate and safer code. It is also common in Berlin teams working across mobile and backend, where one specialist may need to bridge app, API, and shared-domain work.
Ecosystem and tools
Kotlin work often touches Gradle, coroutines, Flow, Ktor, Spring Boot, Jetpack Compose, and serialization tools. Strong professionals know how to balance idiomatic Kotlin with the surrounding stack, not just the language itself. They also understand testing, linting, and dependency management.
When to bring in freelancers
Companies bring in Kotlin specialists for migrations from Java, Android modernization, performance issues, and new product builds. Freelancers are also useful when a team needs short-term help with architecture, code reviews, or stabilizing a release. They can join remotely or on-site in Berlin when tight collaboration is needed.
Signs you need help
- The codebase mixes Kotlin and Java without clear rules
- Android or backend teams disagree on patterns and structure
- Coroutines, state handling, or testing are inconsistent
- Delivery slows during a migration or platform shift
A good specialist leaves the codebase easier to read and safer to change. That matters whether the work is in a startup app, a larger platform, or a shared internal service.
What strong experts deliver
Strong Kotlin professionals write clear code, choose the right abstractions, and keep asynchronous work understandable. They know when to use coroutines, data classes, sealed types, and extension functions, and when to keep things simple. In Berlin, they often work with product, design, and backend specialists across English-speaking teams.
Frequently asked questions
Key details about Kotlin, drawn from the questions we get asked most.
Kotlin is used for Android apps, server-side services, shared business logic, and library code on the JVM. Many teams also use it for Kotlin Multiplatform when they want to reuse domain logic across mobile products. It is a strong fit when readability, null safety, and maintainable code matter.
Kotlin is usually chosen when teams want less boilerplate, safer null handling, and modern language features. Java still appears in many codebases, so the best specialists can work in both and move between them cleanly. For migrations, look for someone who can improve code without forcing a big-bang rewrite.
Kotlin Multiplatform makes sense when shared logic is valuable, especially for networking, domain rules, and data handling across Android and iOS. It is not the right answer for every screen or every team process. A strong specialist will help decide what should be shared and what should stay native.
A strong Kotlin specialist usually knows Android Studio, Gradle, coroutines, Flow, testing tools, and one backend stack such as Spring Boot or Ktor. For mobile work, Jetpack Compose and lifecycle patterns matter a lot. For server work, API design and observability are often key.
A small feature task may only need a focused Kotlin professional, but migrations, architecture changes, or shared-code setups need someone with deeper system experience. The real question is not years on paper. It is whether the person has handled the same kind of delivery risk before.
Yes, Kotlin work is often done remotely, especially for backend services and clearly scoped mobile tasks. Berlin teams also mix remote work with on-site sessions for architecture, planning, or release support. If the project depends on fast feedback across product and design, a hybrid setup can help.
Look for clear code samples, practical migration stories, and good explanations of trade-offs in Kotlin code. Strong specialists can discuss coroutine use, state handling, testing strategy, and how they keep code readable for the next person. They should also show how they work with existing conventions instead of imposing a new style too early.
No, Kotlin is important for Android, but it is also widely used for backend services and shared platform logic. Many teams choose it because they want one language that works well across mobile and server code. That makes it useful for product teams that need consistency across the stack.
The average hourly rate of freelancers in Berlin, Germany who have used Kotlin in their recent projects is 96 €, which corresponds to a daily rate of about 765 € based on an 8-hour working day.
Of the freelancers in Berlin, Germany who have used Kotlin in their recent projects, 97% hold at least a Bachelor's degree, 59% hold at least a Master's degree, and 9% hold a doctorate.
On average, freelancers in Berlin, Germany who have used Kotlin in their recent projects have 18 years of professional experience, with a single engagement typically lasting around 2 years.
The most common languages among freelancers in Berlin, Germany who have used Kotlin in their recent projects are English (98%), German (95%), and French (14%).
The most common industries among freelancers in Berlin, Germany who have used Kotlin in their recent projects are Information Technology (95%), Retail (48%), 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 (50%).
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 
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Cologne 
Frankfurt 
Dusseldorf Request a free demo
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Philipp Thomaschewski
FRATCH CEO
