OpenAPI Experts in Frankfurt
in minutes from over 15,000 CVs with vetted, available specialists.Hire experts who design clear OpenAPI specs, build reliable API contracts, and keep documentation in sync with real endpoints. They help teams using Swagger and the OpenAPI Specification deliver clean integrations, stronger testing, and faster partner onboarding with precise matching and vetted, available freelancers.
Meet FRATCH Experts in Frankfurt, who have recently used OpenAPI
Waseem Sattar
Last position:
Solution Architect / Subject Matter Expert at FRMCS terminal device manufacturer
Participation in the EU-funded MORANE-2 project to validate the Future Railway Mobile Communication System (FRMCS) in real-life use cases: creation of the requirement specifications for TOBA as well as the associated test specifications.
Technologies: 5GS (Radio & Core), FRMCS, MCx (MCPTT, MCData, MCVideo), MC Gateway UE, MCx Priority/Security/QoS Management, ETCS, SIP, IMS
Saqib Javed
Last position:
AI Developer / AI Engineer (Lead) at KOM4TEC GmbH
- Conceptual design and implementation of modular AI assistants for sales and business processes in the Microsoft ecosystem (Agentic AI, Copilot extensions)
- Frontend architecture and development with React + TypeScript for embedded chat and assistant surfaces (streaming UI, hooks, React Query, OpenAPI clients)
- Enterprise-level agent development: reusable skill/agent library, MCP server, review and compliance gates
- LLM integration into the user experience: Anthropic (Claude), OpenAI, tool use, RAG pipelines, prompt engineering, guardrails
- Architecture and code review consulting as well as mentoring in the AI development team
- Integration with Microsoft Graph, Power Platform, and Azure services
- Technologies: React, TypeScript, Anthropic Claude, OpenAI, MCP, RAG, Microsoft Graph, Power Platform, Azure
Uday Vanaparthy
Last position:
Full Stack JAVA Developer & DevOps Engineer at Deutsche Börse (DBAG)
Project: SCS (Settlement / Clearing Services)
Settlement platform serving multiple trading and clearing venues — counterparty risk safeguarding, settlement volume reduction, central risk management, and post-trade anonymity.
Technologies: Java 17, Spring Boot 3, Microservices, Spring Data JPA, SonarQube, Fortify (SCST), Mockito, Jenkins, OpenShift, Maven, Podman, GitHub, JIRA, Liquibase, Swagger, AMQP, Apache Camel, Terraform, PostgreSQL, Instana, Graylog.
- Identified and remediated CVEs in third-party libraries using SCA tooling, strengthening the security posture of production components.
- Maintained 90% code coverage with SonarQube, improving code quality and reducing production defects.
- Built and customized Helm charts and values.yaml configurations across 3 environments (ACT, SIMU, PROD), increasing deployment flexibility and consistency.
- Enabled mTLS for database authentication and message broker connections, enforcing encrypted, certificate-validated communication.
- Designed and deployed microservices with asynchronous, REST-based communication between components.
- Automated build and continuous integration pipelines using Maven and Jenkins.
- Used Podman and OpenShift for container orchestration and Liquibase for database version control.
- Optimized Java code and implemented EHCache-based caching, improving application performance.
- Managed application images, JAR versions, and dependencies via DBAG Artifactory Repository Manager.
Ingo Dettling
Last position:
Analytics at BaFin - Federal Financial Supervisory Authority Frankfurt
- Introduction of methods for developing and automated deployment of cloud-native software and machine learning applications in OpenShift clusters
- Development of various programs in Python
- Technologies: Kubernetes, OpenShift, Kustomize, ArgoCD, Tekton, Docker, PodMan, Airflow, IntelliJ, PyCharm, Git, Bitbucket, Jira, Confluence, Python
Werner Keil
Last position:
Test Coordinator, Designer and Engineer at IBM
- Testing the SekIDP and related components
- Test design, execution and automation, microservices, GitHub Enterprise, Eclipse, Katalon Test Platform, API Testing, Confluence 8, JIRA/Xray, Draw.io, Swagger/OpenAPI, Postman, Docker, Kubernetes, Podman, PuTTY, E-Health, Telematik, Gematik standards, EPA, E-Rezept, sektoraler IDP, encryption, XaDES, PaDES, DICOM, HL7, FHIR, IHE, ICD, SSO, SAML/Shibboleth, OAuth, smartcards, JWT, two factor authentication Android and iOS, Wireshark, BrowserStack, Cypress, gRPC, REST, SOAP, WS-Security, Linux Shell, PowerShell, SSH/SSL, Java, Kotlin, Cordova, Gradle, Groovy, Python, TypeScript
Jonas Walter
Last position:
Fullstack Developer at Soulven Agency
- Working for customer and internal projects ranging from B2C, B2B applications
- Development and maintenance of customer-facing and internal applications across B2C and B2B domains
- Responsibility for technical direction, architectural decisions and code quality standards
- Design and implementation of scalable application architectures, including modular frontend and service-oriented backend structures
- Conceptual planning and technical execution of the agency website relaunch in Angular
- Rapid prototyping and MVP development for B2B customer projects in the pharmaceutical sector with Vue.js
- Creation of first MVPs for 3D rendering–based products, including real-time visualization and interactive experiences
- Strong UX/UI expertise with a focus on gamification, user engagement and conversion-driven interfaces
- Close collaboration with product management, design and stakeholders to translate business requirements into technical solutions
- Agile software development using Scrum, including sprint planning, reviews and retrospectives, supported by Azure DevOps
- Full-stack development using React, Angular, TypeScript, Vue.js, HTML5, CSS3/SCSS, C#, .NET, Node.js, RESTful APIs, Unity, Azure DevOps, Git and CI/CD pipelines
Timur Yalcin
Last position:
Lead Frontend Developer | Fullstack Developer at Finanz Informatik
- Further development of an application for managing personnel changes.
- Development of frontend and backend.
- Implementation of the frontend with React and Material UI.
- Implementation of the backend with Java and Spring Boot.
- Use of React, Java, Spring, TypeScript, next.js, Material UI, Github Enterprise, Figma, Docker, Playwright, swagger, swagger UI, OpenAPI, npm, yarn, git.
Felix Tschöpe
Last position:
Quality and Process Manager Trading – Systems Focus at Mainova AG
- Ensuring stable operation of business-critical applications in the energy environment (KRITIS-adjacent systems), coordinating with IT operations on certificates, permissions, and security-relevant logging
- Continuous monitoring of interfaces, processes, and system states including analysis of deviations and performance issues
- Development and setup of secure interfaces including authentication and access concepts
- Incident management: prioritization, root cause analysis, coordination of issue resolution with IT operations, business units, and external service providers
- Change and release management including coordination, test coordination, go-live, and post-live support
- Product owner for operational systems in day-to-day operations (forecasts, schedule management, market data import and export, contract management, regulatory reporting)
- Documentation of operational processes, changes, and incidents to ensure traceability and auditability
- Automation and digitization of operational processes
- Introduction and use of AI-supported analysis and monitoring approaches and agents with Microsoft 365 Copilot
Ralitsa Popova
Last position:
Process, Project and Requirements Manager, Client Project @ RUBINLAKE at 1&1 Versatel GmbH
- Introduction of a new workflow tool for fibre connectivity & broadband delivery
- Requirements design, estimation and prioritization
- Creation of rollout and project plans
- Managing the development team using Scrum
- Design and project management of the API interface to existing tools
- Process modeling for the new order dispatching teams (FCD & BD)
- Designing processes inside and outside the team
- Requirements design and implementation of necessary tools
- Creation and calculation of production KPIs
Igor Propisnov
Last position:
Senior Frontend Developer at Objego GmbH
Within the project, Objego's digital platform for real estate management was further developed.
Further development of various software modules within the application.
Continuous improvement and optimization of existing functionalities to enhance performance and user experience.
Design and implementation of unit tests to ensure code quality and stability.
Close collaboration with the QA team to quickly fix bugs.
Implementation of new features in coordination with stakeholders and end users.
Active member of the Scrum team with a focus on agile methods and continuous improvement of the software.
Technologies: Angular 16/17, Material, Angular CDK, Angular Elements, Nx, NgRx, NgNeat, NgX-Translate, NgX-Charts, NgX-Lottie, NgX-Markdown, Sentry, Azure AI Form Recognizer, Lodash, Dayjs, Flatpickr, Lottie-Web, Mixpanel, RxJS, Prettier, ESLint, Webpack, Cypress, Playwright, Jest, Husky, TypeScript, Node.js, Zone.js, Docker, Spring Boot, Git, Figma, Figma Token, Storybook, Jira, Confluence, Atlassian, Gitlab CI/CD, Codecov, Custom Design System, Mockoon.
Discover over 15,000 top freelancers
Statistics of experts using OpenAPI
Aggregated from the professional profiles of matched freelancers.
Experience
18 years (Germany: 19 years)
Position duration
2.2 years (Germany: 1.8 years)
Positions per freelancer
15 (Germany: 14)
Top business areas
Information Technology, Product Development, Project Management
Top industries
Information Technology, Banking and Finance, Telecommunication
Certification focus areas
Information Technology, Project Management, Operations
Bachelor's degree or higher
86% (Germany: 89%)
Master's degree or higher
43% (Germany: 50%)
Certifications per freelancer
1 (Germany: 2)
Most common languages
German, English, Russian
Speak two or more languages
100% (Germany: 93%)
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 Frankfurt 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 Frankfurt using OpenAPI
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
OpenAPI is the standard way to describe REST APIs in a machine-readable format. It gives teams one shared contract for endpoints, request bodies, responses, authentication, and error states. Strong specialists use it to reduce ambiguity before implementation starts.
Typical work
- Create or refine OpenAPI documents for new services
- Keep Swagger UI and API docs aligned with code
- Review endpoints for consistency and naming
- Support partner and internal API onboarding
It is common in product teams that ship public APIs, internal service APIs, and integration layers.
Tooling stack
OpenAPI work often sits with Swagger Editor, Swagger UI, Redoc, API gateways, and test tools that read the contract. Specialists also connect it with code generators, linting rules, and CI checks so the spec stays useful after release. Good work is not only writing YAML; it is keeping the contract alive.
When to bring help
Companies bring in freelance expertise when API docs are outdated, integrations keep breaking, or a new platform needs a clean contract model. Frankfurt teams often need this for banking, logistics, travel, and enterprise software, where internal and external systems must agree on data and behavior. Remote collaboration works well, but on-site sessions help when many teams share one API.
What strong specialists do
Strong OpenAPI professionals think in contracts, not just files. They can map business flows to endpoints, model reusable schemas, and spot gaps between implementation and documentation.
- Write clear paths, schemas, and responses
- Design authentication and error handling patterns
- Keep docs, tests, and code consistent
- Improve readability for both teams and partners
Good fit
OpenAPI is a strong fit when a company wants predictable API delivery across multiple teams. It also helps when third-party integrations must be stable and easy to consume. The best specialists know how to balance detail, simplicity, and long-term maintainability without turning the contract into noise.
Frequently asked questions
Before you brief your next project: the most common questions about OpenAPI.
OpenAPI is used to define REST APIs in a structured contract that both people and tools can read. Teams use it for documentation, validation, mocking, code generation, and contract-first design. It is especially useful when several experts need one shared view of how an API should behave.
OpenAPI is the specification; Swagger is the older name many people still use for the surrounding tools and ecosystem. In practice, searchers may mean the same thing when they say Swagger docs or Swagger UI. A good specialist understands both terms and can work with either naming.
A strong OpenAPI specialist should be able to model endpoints, schemas, authentication, and error responses clearly. They should also know how to keep the spec aligned with implementation and how to make it useful for testing and integration. Good work makes the API easier to consume, not just easier to describe.
OpenAPI often goes together with REST design, JSON Schema, YAML, HTTP semantics, and API versioning. Many specialists also work with Swagger UI, Redoc, linting rules, and CI pipelines. If the project is larger, experience with gateways, security schemes, and contract testing helps a lot.
The right level depends on how much API design is still open. A small documentation cleanup needs less depth than a contract-first platform with multiple teams and external consumers. For complex systems, you want someone who has handled OpenAPI across design, review, and release, not just written a few spec files.
Yes, OpenAPI work is usually well suited to remote collaboration because the main deliverable is a shared spec and related documentation. For Frankfurt teams, short on-site workshops can still help when product, backend, and integration groups need to agree on one contract quickly. After that, review cycles are often easy to run online.
A good OpenAPI file is consistent, readable, and close to the real behavior of the API. Check whether paths, schemas, examples, and error responses are complete and whether the document is easy to use in Swagger UI or Redoc. A strong specialist will also catch gaps, duplicated patterns, and unclear naming.
Choose OpenAPI when the API matters to other teams, partners, or clients and needs clear rules. Informal notes are often enough for very small internal work, but they break down fast as the number of consumers grows. OpenAPI gives Frankfurt teams a better base for stable integrations and long-term maintenance.
The average hourly rate of freelancers in Frankfurt, Germany who have used OpenAPI 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 Frankfurt, Germany who have used OpenAPI in their recent projects, 86% hold at least a Bachelor's degree and 43% hold at least a Master's degree.
On average, freelancers in Frankfurt, Germany who have used OpenAPI in their recent projects have 18 years of professional experience, with a single engagement typically lasting around 2.2 years.
The most common languages among freelancers in Frankfurt, Germany who have used OpenAPI in their recent projects are German (100%), English (100%), and Russian (20%).
The most common industries among freelancers in Frankfurt, Germany who have used OpenAPI in their recent projects are Information Technology (90%), Banking and Finance (60%), and Telecommunication (60%).
The most common business areas among freelancers in Frankfurt, Germany who have used OpenAPI in their recent projects are Information Technology (100%), Product Development (80%), and Project Management (80%).
Main locations of FRATCH Experts, who have recently used OpenAPI
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 
Stuttgart Request a free demo
Get in touch with the FRATCH team and we will get back to you within 4 hours.
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Philipp Thomaschewski
FRATCH CEO
