Swagger Experts in Cologne
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Meet FRATCH Experts in Cologne, who have recently used Swagger
Marc Smyk
Last position:
Fullstack Developer at PLANT-MY-TREE
PLANT-MY-TREE®-per-order
The application enables Shopify merchants to automatically place tree-planting orders for every incoming order. By integrating ecological contributions directly into the purchase process, the manual effort for tracking and billing reforestation initiatives is eliminated. The system increases transparency for end customers through real-time visualizations of the ecological impact directly in the storefront. The architecture is based on a modular monolith with Spring Boot in the backend and an integrated React app inside the Shopify admin area. The solution uses webhooks to capture order data in an event-driven way and integrates the weclapp ERP system for automated monthly invoicing. An app proxy mechanism provides dynamic statistics such as CO2 compensation and planted trees without any performance loss for the merchant shop.
Tasks:
- Design of the modular software architecture based on Spring Modulith to ensure high maintainability
- Development of the event-driven business logic for evaluating Shopify orders via webhooks
- Implementation of automated invoicing by connecting the weclapp REST API
- Building the frontend using React Router and Shopify App Bridge for native integration
- Design of the database model and implementation of the persistence layer with JPA/Hibernate and Prisma
- Integration of internationalization processes for global use in the frontend and email communication
- Automation of deployment processes using Docker and GitLab CI/CD
Project skills: Java 25, Spring Boot, Spring Security, Spring Modulith, Hibernate, JPA, REST API, PostgreSQL, Maven, Liquibase, React, TypeScript, React Router, Vite, Node.js, Prisma, Zod, Docker, Docker Compose, GitLab CI/CD, Shopify CLI, Shopify App Bridge, Polaris, weclapp, i18next, Lombok, Vitest
Rainer Langbehn
Last position:
Senior IT Consultant, Senior Software Architect, Senior Software Developer, Senior DevOps Engineer at Techniker Krankenkasse
Automation of the database major / minor releases for the TKeasy project
Concept for database major / minor release automation
As-is analysis
Evaluation of Redgate Flyway functionality
Concept creation
Products: Redgate Flyway, GitHub, Quest, Erwin Data Modeller, Oracle, Atlassian Jira, Atlassian Confluence
Skills: Docker, Continuous Delivery, Continuous Integration, Redgate Flyway, Major Releases, Minor Releases
Alexander Rautzenberg
Last position:
Business Analyst at Financial Services Provider Landesbank
The Helaba ATLAS project aims to modernize core systems and make them future-proof. As part of the subproject, the existing legacy system for international payments is being replaced by a modern web-based application.
- Analysis of functional and technical requirements
- Analysis and optimization of business processes
- Process modeling
- Preparation and facilitation of workshops
- Defining project scope and prioritizing requirements
- Business process management (analysis, modeling, and optimization)
- Specification of user stories
- Designing business and authorization concepts
- Testing and acceptance
- Designing mockups in Figma
- Creating the UI/UX style guide for web applications Approach: Scrum (agile) Technologies: Jira, Confluence, MS Teams, Conceptboard, Java, Vaadin, Figma
Jens Hagemeyer-Lee
Last position:
#52 Test Manager in Safety-Critical Infrastructure at Telecommunications Company
- Network elements, network, operational and operator-related systems
- Supporting around 20 different products (managed agile)
- Requirements analysis and management (functional and non-functional)
- Test concept and planning (scope, test phases, effort, schedule, resources, organization, etc.)
- Aligning approach with clients and service providers
- Managing and assisting in creation of test cases for system, integration and end-to-end tests
- Guiding and supporting test execution
- Defect management and planning bug fixes with external providers
- Preparing and facilitating workshops
- Regular reporting and creating automated test reports
- Further development of agile testing methodology and configuration of supporting tools
- Conceptual support in developing a quality seal for rating product and service quality of internal and external providers
- Requirements engineering based on ISO/IEC 25010, Scrum, SaFE
- BMC Remedy, Atlassian Confluence, Atlassian Jira (including plugins Xray, Structure), Microsoft Office (incl. Visio), Obsidian, doxis document management system, Gitlab, Obsidian
Vladimir Maznicenko
Last position:
Developer at Financial services provider
- Support and further development of a framework for developing applications in a banking association: DynS/OSPE
- Migration of the framework to Java 11 and Java 17
- Java8, Java11 and Java17, Spring, Spring-Batch, Spring WebServices, Spring-Security, Spring-Data, JPA, Hibernate, OpenSource libraries etc.
- XML, JAXB, JSON, REST and SOAP services, DB2, Oracle, WebSphere or Liberty AS, FreeMaker, Junit, mock libraries, JaCoCo, Maven, IntelliJ, Eclipse, GitHub, SVN, Jira
Louis Nguenkam
Last position:
Specialist in Adobe Experience Manager & Microservices at Nguenkam Consulting & Engineering
Java 11/21
Springboot
Swagger/OpenApi
Azure Pipelines
Trivy Integration
Apache Sling
OSGI
Java Content Repository (JCR)
Apache Jackrabbit Oak
Adobe HTL
GraphQL
Maven
GitLab
IntelliJ
Azure Cloud
Azure DevOps
Terraform
AEM specialist in the Scrum team
Development and deployment of microservices via Open API interfaces
Operation of microservices in the Azure Cloud
Implementation of AEM modules and integration with microservices
Member of the knowledge transfer team and a backend coordination team
Andreas Kosubek
Last position:
Backend Developer at Univention GmbH
- Developed a SCIM-compliant Python interface to connect external systems
- Expanded and enhanced UCS modules in Python
- Extended and newly developed Helm charts for container orchestration in Kubernetes
- Maintained and further developed CI/CD pipelines in GitLab
- Implemented automated tests with Pytest and Playwright
'Nubus' is based on a microservice architecture, relies on open source technologies, and runs in Docker containers.
UCS is an IAM complete solution based on Debian, used as an alternative to Microsoft's Active Directory. The work was characterized by the close integration of infrastructure and application logic.
Fatih Karakurt
Last position:
Mobile App Developer at ING Belgium
- Part of a squad focused on intensive module development and integration
- Close collaboration with other squads and teams to integrate modules and essential components
- Use of SwiftUI and the Coordinator pattern to develop clean and understandable code
- Creative collaboration with UX designers in Figma and implementation in code
- Industry: Banking
- Project language: English
- Organizational form: Kanban
- Tools: Azure, Confluence, Figma, Teams
- Team size: 40 people
- Version control: Git, GitFlow, Azure
- App Store product: ING Banking
- Programming languages: SwiftUI, Swift
- Patterns: Coordinator, MVVM
- Swift Package Manager
- Localization: Yes
- Testing: XCTest, XCUITest
Andreas Beckers
Last position:
Senior Frontend Developer at Roadex
- Development of an app
- Technologies: React Native, Expo, SupaBase, TypeScript, GitHub, Trello
Allal Kharaz
Last position:
Java Senior Full Stack Developer at Insurance ÖRAG
- Further development of a policy administration system (contract/claims) for the legal expenses insurer ÖRAG.
- My role: Senior Software Developer.
- The team consists of 12 developers.
- Technologies used: Java 8/21, Java EE, Quarkus, WebLogic, JPA, RabbitMQ, JTA, CI, CD, Jenkins, DB2, Maven, Jenkins, GIT (bitbucket) later GitLab, Junit, Elasticsearch, Mockito, Jira, SonarQube, Scrum, React, Workflow
- Migration and modernization of legacy systems: rewrote C and C++ code in Java to improve maintainability, scalability, and performance. Refactored Python into Java, including optimization and integration into modern architectures.
- Study on the use of AI (Codex) for implementing a Java feature. The goal is to compare the time spent and productivity of AI-supported development with a classic implementation by a developer. The results should show how strongly the use of AI affects development time and efficiency.
- Development of the following tariff calculators for the years 2024/2026: private, companies, doctors, farmers, owner-occupied G + H, landlords, traffic, club, top managers, sales representatives, special criminal law, savings bank, municipal, BayGT, doctors, Dehoga
Discover over 15,000 top freelancers
Statistics of experts using Swagger
Aggregated from the professional profiles of matched freelancers.
Experience
22 years (Germany: 19 years)
Position duration
1.6 years (Germany: 1.7 years)
Positions per freelancer
17 (Germany: 15)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Banking and Finance, Transportation
Certification focus areas
Information Technology, Product Development, Project Management
Bachelor's degree or higher
100% (Germany: 89%)
Master's degree or higher
88% (Germany: 54%)
Doctorate
13% (Germany: 10%)
Certifications per freelancer
2
Most common languages
German, English, French
Speak two or more languages
100% (Germany: 97%)
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 Cologne 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 Cologne using Swagger
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
API contracts
Swagger is used to define REST APIs in a clear, shared format. Strong specialists use it to describe endpoints, request and response models, and error cases before or alongside implementation. That helps teams align backend, frontend, and testing work early.
Documentation flow
- OpenAPI specs that stay readable for teams
- Swagger UI pages for interactive API exploration
- Documentation updates that track code changes
- Contract checks for breaking changes
This is why companies bring in freelance experts when docs are messy, versions drift, or an interface needs to be handed over cleanly.
Tooling
The Swagger ecosystem is built around the OpenAPI Specification, Swagger Editor, Swagger UI, and related code generation tools. Specialists know how to shape specs so they work for both humans and tools, not just for one audience. They also understand versioning, schema reuse, and endpoint naming.
When to hire
Cologne companies often need Swagger help during new API launches, platform refactors, and internal standardization work. The same is true for teams that support distributed products across Germany and need clear remote collaboration. A good freelancer can step in for audits, documentation cleanup, or delivery support without slowing the team down.
What strong experts do
- Keep the API contract consistent with the implementation
- Spot unclear models, missing responses, and weak examples
- Improve readability for product, engineering, and external partners
- Support testing, mock services, and client generation
Strong professionals do not just write docs. They make the spec usable in the real delivery process.
Adjacent skills
Swagger work often sits next to REST design, JSON schema, CI checks, and API governance. Many experts also know how to connect it with Spring Boot, Node.js, or gateway-based setups. They should be comfortable reviewing existing services and improving the contract without disrupting release flow.
Frequently asked questions
What clients ask us most about Swagger — answered in short.
Swagger is used to describe REST APIs in a standard, machine-readable way and to generate clear documentation from that description. Teams use it to make endpoints, payloads, and errors easier to understand and test. It is especially useful when several specialists depend on the same API contract.
Swagger is the name many people still use for the OpenAPI ecosystem, but the current specification is OpenAPI. In practice, teams often talk about Swagger UI, Swagger Editor, and an OpenAPI document in the same project. A good freelancer knows the distinction and works comfortably with both terms.
Bring in a Swagger specialist when an API spec needs structure, cleanup, or a proper handoff between teams. This is common during a new service launch, a platform refactor, or when documentation has fallen out of sync with the code. It is also useful when you need contract-first work or better API governance.
A strong Swagger professional usually understands REST design, JSON schema, YAML, and CI or release workflows. Skills in testing, mock services, and code generation are also valuable because they turn the spec into something the team can use. For backend-heavy projects, knowledge of the surrounding service stack matters too.
Swagger focuses on the API contract and its documentation, while Postman is more centered on testing collections and manual requests. RAML is another API description format, but Swagger and OpenAPI are more common in many teams and toolchains. The right choice depends on whether your priority is contract clarity, testing, or design workflow.
Swagger work can start early, even before the implementation is finished, if the team wants a contract-first API. More complex projects need a freelancer who can review existing endpoints, cleanup legacy specs, and align documentation with production behavior. The more services and consumers you have, the more valuable an experienced specialist becomes.
Yes, Swagger tasks are usually well suited to remote collaboration because most of the work happens in specs, reviews, and shared tooling. For Cologne teams, a local expert can still be useful if workshops, stakeholder meetings, or on-site handovers are needed. Many projects combine remote delivery with a few in-person sessions when alignment matters most.
Look for a Swagger freelancer who writes clean, consistent specs and asks good questions about errors, edge cases, and versioning. The best specialists keep the documentation aligned with the implementation and make the API easier to test, consume, and maintain. Ask to see examples of real OpenAPI work, not just a list of tools.
The average hourly rate of freelancers in Cologne, Germany who have used Swagger in their recent projects is 98 €, which corresponds to a daily rate of about 783 € based on an 8-hour working day.
Of the freelancers in Cologne, Germany who have used Swagger in their recent projects, 100% hold at least a Bachelor's degree, 88% hold at least a Master's degree, and 13% hold a doctorate.
On average, freelancers in Cologne, Germany who have used Swagger in their recent projects have 22 years of professional experience, with a single engagement typically lasting around 1.6 years.
The most common languages among freelancers in Cologne, Germany who have used Swagger in their recent projects are German (100%), English (100%), and French (40%).
The most common industries among freelancers in Cologne, Germany who have used Swagger in their recent projects are Information Technology (100%), Banking and Finance (70%), and Transportation (60%).
The most common business areas among freelancers in Cologne, Germany who have used Swagger in their recent projects are Information Technology (100%), Product Development (100%), and Quality Assurance (80%).
Main locations of FRATCH Experts, who have recently used Swagger
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 
Berlin 
Hamburg 
Munich 
Frankfurt 
Dusseldorf Request a free demo
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Philipp Thomaschewski
FRATCH CEO
