Swagger Experts in Cologne
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Meet FRATCH Experts in Cologne, who have recently used Swagger
Emre S.
Last position:
IT Project Manager | SAP E-Invoicing Outbound at Rohde & Schwarz
Project: Introduction of statutory-compliant electronic invoicing (outbound, Germany) in SAP for an international technology group.
- Project management: Planning, steering and reporting of the E-Invoicing outbound rollout across all affected business areas, including budget and resource coordination.
- UAT: Structured user acceptance test with key users per business area, test cases per invoice scenario, and consolidated test results for decision making.
- Defect management: Handover and tracking of defects in Jira, including validation of the generated invoices against the statutory schemas.
- Cutover, go-live and hypercare: Readiness checks and cutover planning aligned with the statutory deadlines, coordination of go-live and stabilization during hypercare.
- Stakeholder management and reporting: Alignment with Finance, Tax, business departments and IT, preparation of status reports and decision papers, and consistent follow-up of open items.
- Change management and documentation: Communicated process changes to the business departments, enabled key users, and created process and compliance documentation to ensure traceability and audit readiness.
Predrag P.
Last position:
Test Developer | Test Automation Engineer at CreditReform
Technologies: Java 25, Selenium, Insomnia, SSO, Gitlab, Jenkins, Docker, Kubernetes, Jira, IntelliJ, Nexus, Oracle, MariaDB, SpringBoot, Grafana, Concept Board, Vue.js, OpenApi, Kotlin. Implementation, maintenance, and enhancement of automated end-to-end regression tests for UI and API interfaces. Appropriate and targeted test automation involving multiple software products, including Java-based Windows applications. Automation of business processes with Selenium, reset jobs, and DB import jobs, as well as creation of test concepts, test case descriptions, and structured defect reporting.
Andreas B.
Last position:
Senior Software Developer at ELIONOVA AG
- Created an application to control measurement hardware with a Tauri application using React.JS and TypeScript on Raspberry Pi
- Developed a cloud application for storing and analyzing measurement results using Spring Boot and React.JS
- Built a Tauri application for printing ZPL labels on Windows
- Technologies: Java, JavaScript, Tauri, Rust, React.JS, AWS, Kubernetes, Docker, GitLab CI/CD, REST API (JSON), Maven, CI/CD, PostgreSQL
Rainer L.
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
Assessment of the current state
Evaluation of Redgate Flyway functionalities
Concept development
Products: Redgate Flyway, GitHub, Quest, Erwin Data Modeller, Oracle, Atlassian Jira, Atlassian Confluence
Knowledge: Docker, Continuous Delivery, Continuous Integration, Redgate Flyway, Major Releases, Minor Releases
Andreas K.
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.
Marc S.
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
Allal K.
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
Alexander R.
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 H.
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 M.
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
André F.
Last position:
GenAI Product Owner at OW Media Solutions GmbH
- Designed and led the development of an automated short-video generation system.
- Built a scalable AWS backend using Step Functions, Lambda, S3, ECS Fargate, and DynamoDB.
- Developed video rendering with OpenCV and FFMPEG; ensured maintainable Python code.
- Supervised and mentored a Python developer and trained the client in AI workflows.
- Decreased end-to-end production time from hours to minutes.
- Created a modular, extensible architecture designed to support future AI models.
Louis N.
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
Jyothikrishna S.
Last position:
Senior Back-end Engineer at RLE Engineering and Services GmbH
- Works at Ford Motor Company as Senior Back-end Developer on contract via outsourcing
- Designed and developed REST APIs based on the analyzed requirements and technical standards
- Investigated issues and defects to determine root causes and formulate corrective action measures
- Participated in QA, stage, and production release activities
- Conducted code reviews for performance improvement
- Provided monitoring and support using GCP
- Used test driven and behaviour driven development approaches
- Took part in agile ceremonies
Fatih K.
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
Discover over 15,000 top freelancers
Statistics of experts using Swagger
Aggregated from the professional profiles of matched freelancers.
Experience
19 years
Position duration
1.8 years (Germany: 1.7 years)
Positions per freelancer
14
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Banking and Finance, Government and Administration
Certification focus areas
Information Technology, Product Development, Project Management
Bachelor's degree or higher
100% (Germany: 90%)
Master's degree or higher
75% (Germany: 54%)
Doctorate
8% (Germany: 9%)
Certifications per freelancer
1 (Germany: 2)
Most common languages
German, English, French
Speak two or more languages
100% (Germany: 98%)
Based on our profile pool as of 29 Oct 2026.
Daily rate distribution
The chart shows how the daily rates of experts in this technology in Cologne 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 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 29 Oct 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
Swagger 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 (93%)
- Banking and Finance (64%)
- Government and Administration (57%)
- Transportation (50%)
- Telecommunication (50%)
- Automotive (43%)
- Retail (43%)
- Education (36%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
API documentation
Swagger is a set of tools for describing, documenting and testing HTTP APIs. Its specifications are now maintained under the OpenAPI Initiative, so teams often use Swagger and OpenAPI together. A clear contract explains endpoints, parameters, authentication, request formats and response schemas before consumers connect to a service.
Core tooling
The Swagger ecosystem includes Swagger Editor for writing and validating specifications, Swagger UI for interactive reference pages, and Swagger Codegen or OpenAPI Generator for creating client and server libraries. Strong specialists also work with YAML or JSON, schema validation, version control and automated documentation pipelines.
Typical use cases
- Create an OpenAPI contract for a new REST service
- Turn existing endpoints into accurate, searchable documentation
- Generate client libraries, server stubs or test data
- Add authentication flows and reusable schema components
- Validate breaking changes in CI workflows
Swagger is most useful when several teams, applications or external consumers depend on the same API. It supports consistent communication between product, frontend, backend and quality teams without replacing careful API design.
When to bring in expertise
Companies often need freelance expertise when documentation is incomplete, an API is being exposed to partners, or a service is moving from informal endpoint notes to a governed OpenAPI contract. Specialists can also help when generated code is unreliable, API versions drift, or a legacy service needs a dependable reference.
For Cologne-based teams, a professional may join on-site workshops or work remotely with distributed product groups. Clear written communication in English or German can matter when specifications are shared across local and international stakeholders.
Quality signals
A capable Swagger professional treats the specification as a maintained product asset, not a one-time file. They clarify ambiguous behavior, model errors and pagination, define security schemes, and keep examples aligned with real responses. They also understand when generated output needs manual review.
Look for experience with contract reviews, pull requests, automated validation and consumer feedback. The strongest specialists connect documentation decisions to usability, compatibility and release processes rather than focusing only on the visual Swagger UI.
Related skills
Swagger work commonly overlaps with REST API design, OpenAPI governance, JSON Schema, OAuth 2.0, API gateways and automated testing. Experience with frameworks such as Spring, .NET, Node.js or Python helps a professional verify that the contract reflects the implementation.
Useful deliverables include an approved OpenAPI file, interactive reference documentation, reusable schemas, migration guidance and CI checks. Ask how the specialist handles versioning, deprecated endpoints, security details and differences between generated examples and production behavior.
Frequently asked questions
What clients ask us most about Swagger — answered in short.
Swagger is used to describe, document and test HTTP APIs through a machine-readable contract and interactive documentation. The tooling can show endpoints in Swagger UI, validate an OpenAPI definition and support client or server code generation.
OpenAPI is the specification standard that evolved from the original Swagger project. Swagger now commonly refers to the surrounding tools, such as Swagger UI and Swagger Editor, while OpenAPI describes the API contract itself.
A strong Swagger specialist usually understands REST design, YAML or JSON, JSON Schema, authentication methods and automated API testing. Familiarity with API gateways, version control and a backend framework helps them keep documentation consistent with the running service.
The right level of Swagger experience depends on the scope. A small documentation cleanup may need solid OpenAPI knowledge, while a public API program benefits from a specialist who can govern versions, model reusable schemas and integrate validation into delivery workflows.
Yes. Swagger work is well suited to remote collaboration because specifications, reviews and validation rules live in shared repositories. Cologne teams may choose remote delivery, on-site workshops or a hybrid setup, depending on stakeholder access and language needs.
Swagger and Postman solve related but different problems. Swagger and OpenAPI center on a formal API contract and generated documentation, while Postman is commonly used for collections, exploratory requests and test execution; many teams use both.
Review whether the Swagger documentation matches real request and response behavior, including errors, security and edge cases. Ask for examples of contract reviews, automated validation, versioning decisions and how consumers influenced the specification.
A Swagger project may deliver an OpenAPI file, Swagger UI documentation, reusable schemas, generated clients, validation checks and migration notes. Agree in advance on ownership, review criteria, supported API versions and how updates will stay synchronized with implementation.
The average hourly rate of freelancers in Cologne, Germany who have used Swagger in their recent projects is 92 €, which corresponds to a daily rate of about 739 € 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, 75% hold at least a Master's degree, and 8% hold a doctorate.
On average, freelancers in Cologne, Germany who have used Swagger in their recent projects have 19 years of professional experience, with a single engagement typically lasting around 1.8 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 (29%).
The most common industries among freelancers in Cologne, Germany who have used Swagger in their recent projects are Information Technology (93%), Banking and Finance (64%), and Government and Administration (57%).
The most common business areas among freelancers in Cologne, Germany who have used Swagger in their recent projects are Information Technology (100%), Product Development (86%), and Quality Assurance (79%).
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 
Frankfurt 
Stuttgart 
Dusseldorf Countries:
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