Retrofit Expert in Germany
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Meet FRATCH Experts in Germany, who have recently used Retrofit
Thorsten Henneberg
Last position:
OCM (Overall Construction Manager) for HVAC at Engie Deutschland GmbH
- Overall planning and supervision of the relevant HVAC and sanitation installations across multiple construction phases.
- Leading installation teams and subcontractors.
- Ensuring adherence to schedules, budgets and quality standards.
- Coordination with other trades.
- Lean Construction Management, preparing and moderating the Last Planner Method.
- Supporting schedule planning and moderating workshops in the IPA project environment.
- Planning, organizing and supervising all HVAC and sanitation work on site.
- Managing own installers and coordinating subcontractors.
- Ensuring that all work meets quality standards, safety regulations and the schedule.
- Aligning with other trades, authorities and the client representative.
- Creating plans and reviewing invoices.
- Monitoring the proper application of construction techniques and compliance with safety regulations.
Thomas Wüst
Last position:
Interim Sales Manager at Inovan GmbH & Co. KG
Situation:
- decline in sales
- need for support in identifying and opening up new sales markets
TASK:
- Expand the B2B network and develop new strategic partnerships to open up additional sales opportunities and new markets.
MEASURES:
- Identify and approach potential B2B customers and partners
- Expand existing contacts in the market environment
- Develop new strategic partnerships
- Customer and market meetings mostly in the field
- Support in opening up new sales opportunities
RESULTS:
- B2B network expanded in a targeted way
- new strategic partnerships initiated
- additional market and sales potential made visible
- stronger presence with customers through personal market work
Malte Lohrberg
Last position:
Product Owner, Change Management Coach and Organizational Consultant & Founder and Product Architect at Freelance + Resilience Bakery
The combined experience from recent project years shows that two hearts beat in my chest: on the one hand, working in and for organizations to develop new, innovative products, ideally as part of a digitization strategy or business development – and the closely related change and transformation process expertise as part of holistic organizational consulting. For this, I have established the Change Bakery and Product Validators offerings.
On the other hand, my heart and mind are fired up to find my own products, evaluate markets and potentials, and test ideas. Currently, I am proactively and part-time, in addition to ongoing projects, working on a product idea in the mental health area and have founded Therapymate.
Paul Privler
Last position:
Independent Consultant – Industry/ Embedded/ IoT at Self-employed
Consulting and support in the areas of sales/business/technology/development/marketing:
- Sales, Key Account Management
- Business Development, business/corporate development
- Partner management
- Program/project management
- Product management & marketing
- Technical marketing, content marketing
- New business, innovation and technologies
Until July 2021 active as advisor and consultant for Mixed Mode in the areas of Key Account Management, Project Management and Business Development.
From Q3/2021 successful delivery of various customer projects in the area of Business Development, corporate development, consulting, coaching, technical content management, sales and marketing:
- EMS service provider and PCB test house, inspection systems: revision of company portfolio and presentation. Integration of specialized distribution for optical inspection systems from Japan: content management, marketing, communication, web, sales automation, lead generation
- Full service marketing agency – technology marketing for industry: expansion of the existing B2B and B2C marketing portfolio with industrial and technology topics: content management, presentation and focus on "technical marketing", web, target market and customer analysis, lead automation, consulting
- Software product manufacturer & software development in the field of security for Embedded & IoT: company alignment and portfolio definition for an IoT and Embedded Security company with a SaaS solution for IoT device management: building a partner network to offer complete Embedded/IoT security solutions, technical content, company alignment and portfolio definition, strategy & planning, target market and customer analysis, product marketing/USPs for the security device management tool "IoT-Suite", standards and regulations for cyber resilience (e.g. CRA, NIS2, RED), web content, SEO, management of marketing and sales agencies, CRM, sales, presentations, trade fairs, congresses, building company webinars & events
- Software engineering service provider/system house for IoT, Embedded, web, mobile and desktop applications: business development, content creation, customer acquisition and sales
- Manufacturer of memory products with security features as an add-on: memory products in standard form factors (SD, CF, SSD...) are extended with security modules such as HSM, TPM or secure elements and thus offer users secure data storage, transfer and access. Also interesting as an upgrade or retrofit solution to meet the coming new regulations and requirements regarding cybersecurity such as CRA, RED and NIS2. Business & New Business Development for the area "Embedded IoT Solutions & Security", sales & marketing. Expansion of the pure semiconductor business to include security solutions and services. Interface between management, marketing, sales and product management. Building business partners, technology partners, system integrators and resellers from the Embedded, IoT, OT and IT environment. Creating reference designs/demos/lighthouse cases and proof of concepts for cross- and reference selling. Co-marketing with security partners. Technical content creation for web, sales and marketing, webinars, social media etc. Networking, participation in trade fairs, congresses and events. Lead generation, qualification, follow-up and conversion to customer. Product definition, USPs, features. Analysis of competitors, market positioning, target markets - strategy, concept and measures - go to market.
- Marketing agency group with sales and management consulting: consulting for companies on restructuring, market analysis and market entry, go-to-market concepts, customer acquisition and expansion, new customer generation, lead generation and management, concepts and execution of campaigns (web, mail, social media, phone outreach in person or with AI voice assistant, webinars...). Processing and managing customer product data for PIM product information and DAM data asset management systems. Focus on customers in the industrial and technology environment with products and services that need explanation.
Johannes Fruntzek
Last position:
Project Management Conveyor Technology at Amazon Deutschland Transport GmbH
Retrofit of 10 existing distribution centers with ASML (automated scan manual labelling)
Automation of conveyor technology at the induct with the goals of improving ergonomics, reducing costs, and increasing throughput
Adaptation of existing MHE (material handling equipment)
Supplier management (internal and external)
Construction site coordination
Detailed planning and execution of the implementation concept
Acceptance tests for machine safety, Machinery Directive
Planning and execution of IOQ, SWEH, SAT, Launch
Ensuring compliance with costs, deadlines, and scope
Risk management
PM coaching of the project team and suppliers
Leading multiple international teams
International communication/coordination of sites (Delivery Stations AMZL, suppliers), RME, Ops, Safety, PMO, and Quality
Methods and tools: Interim project management, project management (classic, agile, hybrid), change management, V-model, Scrum, Ozark, Chime, PtW, RightCrowd, stakeholder management, scheduling, cost planning, resource planning, controlling, conveyor technology, logistics, mechanical engineering, construction site coordination, claim management, requirements management, specifications, functional specification, supply chain management, risk management, FMEA, lessons learned, supplier management, team leadership, communication (international)
Frank Doerries
Last position:
Project management, development and system integration for retrofit on a Uranus thermionic mass spectrometer at Forschungszentrum Jülich
- Development of a retrofit concept, including qualification measures
- Development, installation and commissioning of the required hardware and software
- Development of a safety concept
- Execution and documentation of in-house verifications / qualification
- Initiation and implementation of measures in case of non-conformities
- Execution of CE conformity assessment procedures and CE marking
Joaquim Landa Miala
Last position:
Freelance ABAP Developer, Logistics at Cheplapharm
- Tested integration of TIBCO EBX with SAP S/4HANA via TIBCO BusinessWorks – proof of concept
- Implemented use case: communication between TIBCO EBX and SAP S/4HANA via IDocs to exchange material master data and business partner data
- Customized, configured, and implemented inbound and outbound processing in the SAP S/4HANA environment for communication with the TIBCO EBX software interface
- Distributed classes, characteristics, and values between TIBCO BusinessWorks and SAP S/4HANA and customized the inbound processing
- Documented the technical components
Ian Stack
Last position:
Sales Representative at Moetefindt Fahrzeugbau GmbH
- In just a few weeks, I became independently able to close deals in a completely new, technically demanding product environment: I qualified incoming online leads (social media, landing page), provided technical advice, prepared quotes, and negotiated contracts (SAP Business One).
- In about seven months, I closed deals worth roughly EUR 340,000, including a semi-trailer for transporting up to four premium SUVs (order value approx. EUR 242,000, including clarification of technical feasibility).
- Left due to operational reasons as part of a restructuring.
Basel Jaber
Last position:
Senior Application Engineer / Product Manager at Altran Magnetics LLC
- Oversee development and optimization of key products, including DP contactors, EMI filters, and circuit breakers.
- Lead certification processes ensuring compliance with UL, TÜV, and VDE standards.
- Act as technical liaison between customers, sales teams, and manufacturing to deliver customized solutions.
Milton Bozoky
Last position:
Interim Project Manager at Amazon
- Developed and implemented comprehensive project plans for the rollout of various MHE systems (e.g., automated forklifts, conveyors) across Amazon’s network, including innovative packaging designs and material innovations.
- Set and coordinated daily milestones with both internal teams and external vendors.
- Ensured continuous alignment among warehouse operations, technical teams, and external partners through regular progress meetings, maintaining complete project transparency.
- Directed comprehensive activities including employee training led by the Learn team, performed detailed machine parts checklists to verify compliance, and monitored setup adherence to safety and operational standards.
- Implemented robust end-to-end testing protocols, monitored key performance indicators, and facilitated a seamless transition from project completion to regular operations with thorough documentation.
Frank Baier
Last position:
Subproject Lead Control Technology at Aumann Beelen GmbH
- Concept creation and detailed design for a battery module assembly line
- Commissioning coordination at a large Bavarian automotive manufacturer
Tilman Gühring
Last position:
Interim Manager at KAYSER Filtertech GmbH
- Managed two plants in the Czech Republic with 120 employees and €20 M revenue after a failed relocation
- Stabilized processes and significantly improved technical performance
- Reduced order backlog by 40%
- Responsible for order processing and continuation of controlling
- Integrated the plant into SAP
Umer Dilpazir
Last position:
Activation and Vocational Integration Program with Integrated Language Support at Berlitz
- Intensive language course with a focus on professional language content.
Radislav Zak
Last position:
Interim Project Manager at ZakZak Engineering (Client: Eco Energy Future AG)
Retrofit of wind turbines with innovative technologies
Set up a project management system based on Atlassian software with the Work Management and Confluence modules
Developed a workflow for the proposal process for retrofitting existing wind turbines (WKA) and photovoltaic systems (PVA)
Created business cases and business plans
Tracked deadlines and content of the project and piloted the workflow in client projects
Ensured stakeholder acceptance of the project management system
Introduced and consistently applied agile methods, such as Kanban
Met deadlines and delivered content for the set milestones
Acquired industry knowledge
Successfully implemented Atlassian software
James Cullimore
Last position:
Freelance Android Developer at Normalis
- Working on Telecommunication Apps on Android under NDA for the Military
- Participation in the development of backend services (Spring, Java)
- Android Development, Kotlin, Compose, REST, JSON, State-Machines, Android Studio, IP Communication, Cybersecurity, Agile
Discover over 15,000 top freelancers
Statistics of experts using Retrofit
Aggregated from the professional profiles of matched freelancers.
Experience
21 years
Position duration
4.4 years
Positions per freelancer
11
Top business areas
Product Development, Information Technology, Project Management
Top industries
Information Technology, Manufacturing, Automotive
Certification focus areas
Information Technology, Product Development, Quality Assurance
Bachelor's degree or higher
81%
Master's degree or higher
48%
Doctorate
7%
Certifications per freelancer
2
Most common languages
German, English, French
Speak two or more languages
94%
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 Retrofit
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
Type-Safe HTTP Communication for Android and Java
Retrofit is the industry standard for turning REST APIs into Java or Kotlin interfaces. It simplifies network operations by translating API endpoints into executable code, eliminating boilerplate. Specialists use it to build clean, testable network layers that communicate seamlessly with backend systems.
Core Ecosystem and Serialization Tools
The library relies on a robust network stack and serialization ecosystem to handle modern web requests.
- OkHttp for managing network calls, interceptors, and connection pooling.
- Serialization libraries like Moshi, Gson, or Kotlinx Serialization for JSON parsing.
- RxJava and Kotlin Coroutines for asynchronous flow control.
- MockWebServer for reliable network layer testing.
Key Deliverables of Retrofit Specialists
Professionals design architecture that makes API communication predictable and secure. They deliver production-ready configurations, including token refresh interceptors, custom error handling adapters, and optimized caching strategies. These configurations minimize battery consumption and data usage on mobile devices.
Application in the German Enterprise Landscape
Many organizations in Germany, particularly in the automotive, logistics, and fintech sectors, rely on native Android applications for their daily operations. Experts configure the network layer to handle strict local security requirements, on-premise gateway integrations, and offline synchronization in regions with low connectivity.
Signs Your Project Requires External Expertise
Legacy mobile applications and complex API integrations often benefit from dedicated technical support.
- Your mobile application suffers from slow or unreliable API request handling.
- The current codebase contains redundant boilerplate code for simple HTTP calls.
- Security audits require implementing certificate pinning or advanced OAuth flows.
- You are migrating a large Android application from legacy network clients.
What Distinguishes Top Retrofit Professionals
The best specialists do not just write API interfaces; they understand the entire HTTP lifecycle. They design robust error-handling mechanisms that survive network dropouts and write clean unit tests for every network scenario. Their expertise ensures that your application remains responsive and secure under any network conditions.
Frequently asked questions
What clients ask us most about Retrofit — answered in short.
Retrofit is a type-safe HTTP client used to connect Android and Java applications to RESTful web services. It translates API endpoints into reusable interfaces, reducing boilerplate code and making network operations highly readable. Professionals use it to handle JSON parsing, request headers, and async network operations securely.
While Volley is good for basic image loading and fast request queuing, Retrofit excels in large-scale architecture because of its type safety and clean interface structure. Ktor is a strong alternative for multiplatform Kotlin projects, but this framework remains the default choice for pure Android development due to its mature ecosystem and robust integration with OkHttp.
Most experts working with Retrofit prefer Moshi or Kotlinx Serialization over older options like Gson. Moshi is built specifically for Kotlin and Java, offering better performance and safer null-handling. Choosing the right converter depends heavily on your data structure and performance requirements.
Retrofit specialists in Germany usually work remotely, as network layer configuration and API integrations do not require physical hardware. However, for initial architectural planning or integration tests with local IoT devices, many experts are open to hybrid setups.
Yes, Retrofit supports multipart requests for file uploads and stream processing for large downloads. Professionals configure custom interceptors to track upload progress and manage memory efficiently when handling large media files.
Authentication is typically handled by pairing Retrofit with OkHttp interceptors. Specialists implement authenticator classes that automatically detect expired JSON Web Tokens and request fresh ones without interrupting the user experience.
Yes, modern Android development pairs the Retrofit framework with Kotlin Coroutines for asynchronous programming. This combination avoids blocking the main user interface thread and makes asynchronous network calls look synchronous.
For projects in Germany, compliance with GDPR regulations requires secure data handling in transit. A qualified specialist will configure Retrofit to use certificate pinning, strict TLS versions, and masked logging to prevent sensitive user data from being exposed.
The average hourly rate of freelancers in Germany who have used Retrofit 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 Germany who have used Retrofit in their recent projects, 81% hold at least a Bachelor's degree, 48% hold at least a Master's degree, and 7% hold a doctorate.
On average, freelancers in Germany who have used Retrofit in their recent projects have 21 years of professional experience, with a single engagement typically lasting around 4.4 years.
The most common languages among freelancers in Germany who have used Retrofit in their recent projects are German (94%), English (92%), and French (17%).
The most common industries among freelancers in Germany who have used Retrofit in their recent projects are Information Technology (69%), Manufacturing (58%), and Automotive (50%).
The most common business areas among freelancers in Germany who have used Retrofit in their recent projects are Product Development (81%), Information Technology (72%), and Project Management (69%).
Main locations of FRATCH Experts, who have recently used Retrofit
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 
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Philipp Thomaschewski
FRATCH CEO
