REST API Experts in Essen
matched in minutes from over 15,000 CVsHire experts who design resource-based interfaces, secure integrations and documented services with REST API, OpenAPI and OAuth. Find vetted, available freelancers with the precise skills your project needs through fast AI matching.
Meet FRATCH Experts in Essen, who have recently used REST API
Fadi S.
Last position:
Development of a production-ready Enterprise Document AI & Recommendation Platform at Freelancer
- Development of a production-ready Enterprise AI solution for the automated processing of invoices and business documents
- Integration of Azure AI Document Intelligence and LLM technologies into existing business processes
- Development of robust REST APIs for automated document processing and system integration
- Extraction, validation, and storage of structured invoice data in Azure SQL as a base for analytics and machine learning models
- Development of an AI-based recommendation engine with machine learning and deep learning to generate personalized product recommendations based on historical purchase data
- Implementation of logging, monitoring, error handling, and validation mechanisms for stable production use
- Collaboration with business teams to define business rules and integrate the solution into existing enterprise processes
Technologies: Python, Azure AI Document Intelligence, Azure OpenAI, Azure SQL Database, REST APIs, Machine Learning, Deep Learning, OCR, Pandas, JSON, Workflow Automation
Boris S.
Last position:
Generalist expert for software development at Mercor
- Training AI models, evaluating images and text UI/UX, turning the provided data into insights through OpenAI Feather as part of the machine learning workflow
Technologies: OpenAI Feather
Daniel A.
Last position:
Sales Development Representative (SDR) at TenderFlow GmbH
- Acquires new B2B customers for an AI SaaS startup in the public tendering space and books product demos with IT decision-makers.
- Qualifies target customers based on a defined ideal customer profile, including discovery, needs analysis, and objection handling.
- Builds domain knowledge in public procurement (EVB-IT, German and EU procurement portals) for conversations on equal footing.
Laurin H.
Last position:
Software Architect (Freelance) at Care4Sure
- Delivered MVP-focused full-stack architecture for a health-sector client: Vite/React frontend, backend services on Google Cloud Run, and Supabase for database plus IAM/authentication.
- Supported product requirements engineering and prioritized cost-aware workload placement, implementing browser-side/edge computation where feasible before moving logic to backend services.
Anupriya P.
Last position:
Senior Software Engineer at Telefonica Germany
(Maternity/Parental Leave: July 2023 – Aug 2024)
- Domain: Payment Domain | Client: Telefonica Germany
- Project: General Payment Service
The General Payment Service is responsible for processing of online payments via external payment service provider like Safer pay and PayPal
- Developed Design of Use (DOU) and interface contract documentation, ensuring clarity and compliance across system integrations
- Designed and delivered REST/SOAP web services with Spring Boot and Spring Data JPA, publishing Swagger contracts through WSO2 API Gateway to improve accessibility and governance.
- Spearheaded the on-premises to AWS Cloud migration, re-platforming from Oracle to PostgreSQL on AWS RDS and deploying services on EC2, improving scalability and cost efficiency.
- Containerized microservices using Docker and orchestrated deployments with Kubernetes, streamlining deployment pipelines and improving system reliability.
- Implemented proactive monitoring and logging via AWS CloudWatch and Kibana, ensuring stability and performance during cutover.
- Enhanced collaboration through code reviews and peer reviews, promoting maintainability and clean coding standards.
- Strengthened quality by writing comprehensive JUnit tests and preparing detailed test cases enabling early defect detection
- Delivered automated API testing with Ready API, Postman, and SOAPUI, and conducted performance testing with JMeter, ensuring reliability in high-transaction environments.
Celil U.
Last position:
ZÜRS Geo 2021 at adesso SE
- Frontend development
- Spring Boot
- Swagger
- Git
- GitLab
- SonarQube
- Docker
- Maven
- Java
- Angular
Sandra R.
Last position:
FRONTEND DEVELOPER at easy Marketing GmbH
- Development and enhancement of scalable Vue.js/TypeScript applications, as well as reusable components and frontend architectures
- Development of modern, high-performance web applications for internal software solutions using Vue.js, Pinia, and Vuex
- Efficient integration and processing of data from external APIs to support frontend development and ensure smooth end-to-end functionality
- Implementation and maintenance of automated tests for quality assurance using Vitest
- Creation of interactive website prototypes in Figma and Adobe XD as a basis for Vue.js implementations
- Participation in technical reviews and code reviews to ensure high code quality and continuously improve development processes
- Use of AI-supported development tools such as ChatGPT and Claude for more efficient development, error analysis, and code optimization
- Use of CI/CD pipelines for the efficient integration of automated tests, builds, and deployments into the development workflow
Adem S.
Last position:
IT Consultant (Test Manager) & CEO at Trikolon Consulting GmbH
- Development and implementation of test concepts for complex, multi-layered systems
- Creation of regular management reports and presentations for stakeholders and clients
- Technical and disciplinary leadership of international test teams (coordination, coaching, resource planning)
- Responsibility for quality assurance across multiple test levels (unit, integration, system, and acceptance tests)
- Design of test cases and test plans in Azure DevOps; ensuring traceability and coverage
- Use of BDD approaches (Gherkin/Cucumber) to prepare test automation
- Building a test automation architecture with Playwright and integrating new tests into CI/CD pipelines
- Performing API tests (REST) and tests for mobile/PWA applications
- Setup and maintenance of test environments across multiple stages (integration, QA, UAT, pre-production)
- Test data management (synthetic and production-like data), ensuring consistency and reproducibility
- Collaboration with DevOps teams for containerization (Docker/OpenShift) and CI/CD integration
- Working under SAFe & Scrum, closely coordinating with product owners and DevOps teams
- Active participation in PI plannings, sprint reviews, and retrospectives
- Promoting an agile QA culture through coaching and knowledge sharing
- Introducing scalable test automation with Playwright → significant reduction of manual testing efforts
- Increasing test transparency through clean defect and reporting management in Azure DevOps
- Improved release quality through an end-to-end QA strategy and automated regression tests
- Strategic leadership of Trikolon Consulting GmbH and responsibility for finance, personnel, and business development
Mike H.
Last position:
IT-Consultant & Founder at QFITS GmbH
In my role as Managing Director of QFITS GmbH, I support companies throughout the entire project cycle - from requirements gathering and process analysis to the design of suitable system solutions and all the way to implementation and quality assurance. My focus is on the introduction and integration of POS and ERP systems as well as their seamless connection to existing backend systems and interfaces.
Direct food sales (09/2025 – 05/2026) Support of a project from requirements analysis to the introduction and integration of a new POS system for a direct food sales company. A special focus was on archiving POS logs as well as preparing and providing them as transactions for connected surrounding systems. In addition, design and setup of functional tests and performance tests for the existing backend system, which had to be seamlessly integrated with the POS system.
Ahmet C.
Last position:
Senior Android Developer at enbw
- Support in restructuring and designing the group's internal Android apps
- Defining essential modules and implementing accessible components
- Establishing agile approaches at an international level
- Technologies & Methods: Kotlin, Android, JUnit 5, Koin, Azure DevOps, Android Studio, Git, Jetpack Compose, Coil, Flow API, Ktor, Coroutines, TypeScript, Node.js
Gernot L.
Last position:
Founder and Managing Director at Softwerk/Ruhr GmbH
- Architecting and developing SaaS platform for graphical definition and execution of pandas data processing pipelines
- Developed POlyglott, an open-source Python CLI tool for translation workflow management featuring PO file parsing, quality linting with glossary enforcement, and DeepL API integration for machine translation
- Developed web application for material compliance management (EU REACH) using Django and modern web technologies
- Built automated infrastructure platform using Proxmox, Terraform, and Ansible — VM provisioning, configuration management, internal DNS, and fleet-wide security hardening across multiple subnets
Andreas A.
Last position:
IT-Application Manager at IHK-GfI
- Gathering, analyzing, specifying, and prioritizing requirements for the 'Archive and Delete' module of the Chambers of Industry and Commerce in a Scrum team
- Capturing and specifying screen/form designs, functionality, and data types in Confluence, as well as creating user stories in Jira
- Preparing PowerPoint presentations for the 'Archive and Delete' module
- Coordinating and supporting the Chambers of Industry and Commerce in the implementation of the module
- Writing SQL scripts for an Oracle database
- Technologies used: Scrum, Confluence, Jira, MS Office, Postman, JavaScript, REST API, JSON, DBVisualizer, SQL
Hendrik L.
Last position:
Senior Modernization Engineer – Legacy Web App Performance & Refactoring (Energy Sector) at Levering IT GmbH
Re-architected a web application that had grown over years, modularizing tightly coupled components
Reduced response times from several seconds to <50 ms
Removed performance bottlenecks
Simplified architecture so internal teams can implement features on their own again
Loic N.
Last position:
Development of an app for managing Power Platform components at Hays GmbH
- Requirements analysis
- Provisioning of SharePoint sites and permissions
- Provisioning of SharePoint libraries and lists as data storage
- Development of the UI with Power Apps
- Development of automations with Power Automate to transfer data from Power Apps using Dataverse connectors
- Creation, customization, and management of Power Platform security roles
- Creation and management of Power Platform pipelines
- Development of UX design with Power Apps
Musa M.
Last position:
Qa Engineer at TD Bank
- Designed and implemented an automation test framework using Junit and Maven, developing BDD scripts with Cucumber and reusable methods for application behavior.
- Created test data using automation scripts with Selenium WebDriver, Java, and Python, validating UI components, popup windows, and mouse movements.
- Conducted API functional testing of RESTful web services using Postman.
- Automated test execution using Maven and integrated with Jenkins, achieving a 20% reduction in regression testing time.
Discover over 15,000 top freelancers
Statistics of experts using REST API
Aggregated from the professional profiles of matched freelancers.
Experience
15 years (Germany: 17 years)
Position duration
1.9 years (Germany: 2.9 years)
Positions per freelancer
10 (Germany: 12)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Banking and Finance, Transportation
Certification focus areas
Information Technology, Project Management, Product Development
Bachelor's degree or higher
95% (Germany: 92%)
Master's degree or higher
62% (Germany: 55%)
Certifications per freelancer
2 (Germany: 3)
Most common languages
German, English, Spanish
Speak two or more languages
100% (Germany: 97%)
Based on our profile pool as of 19 Sep 2026.
Daily rate distribution
The chart shows how the daily rates of freelancers in this technology in Essen 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 Essen using REST API
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 19 Sep 2026. Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.
REST API 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 (96%)
- Banking and Finance (50%)
- Transportation (33%)
- Manufacturing (33%)
- Professional Services (33%)
- Automotive (29%)
- Energy (29%)
- Education (25%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
What REST API Does
REST API is a web interface style for exchanging resources through standard HTTP methods such as GET, POST, PUT and DELETE. It commonly returns JSON and connects browser applications, mobile apps, partner systems and internal services. A well-designed API keeps clients and business logic loosely coupled.
Where It Fits
Companies use REST API to expose customer data, orders, payments, inventory and workflow actions across distributed systems. It supports public services, internal applications and integrations with SaaS products. In Essen, specialists may contribute to manufacturing, logistics, retail, healthcare or energy systems, working remotely or alongside local product teams.
Ecosystem And Tools
Strong REST API work includes more than routing requests. Typical tooling and adjacent skills include:
- OpenAPI or Swagger documentation and contract review
- OAuth 2.0, JWT, API keys and role-based access
- PostgreSQL, MongoDB or other persistence layers
- Docker, CI pipelines, logging and observability
- Postman, automated tests and service virtualization
When To Bring In Experts
Freelance expertise helps when an API is slow to evolve, difficult to document or breaking client applications. It is also valuable during a platform migration, a partner integration or the separation of a monolith into services. Companies often need a specialist to define resource models, versioning rules and a practical delivery plan.
What Good Delivery Includes
A capable REST API professional turns business actions into consistent endpoints with clear status codes, validation and error responses. They consider pagination, filtering, idempotency, rate limits and backward compatibility before implementation. They also test unhappy paths and make the interface understandable for every consuming team.
How Quality Is Judged
Review API contracts, sample requests and responses, test coverage and decisions around security. Look for experience tracing failures across HTTP clients, gateways, databases and downstream services. For remote collaboration, clear written communication matters; for Essen-based teams, German or English capability can support workshops and handovers. The best specialists explain trade-offs instead of treating REST as a fixed recipe.
Frequently asked questions
Before you brief your next project: the most common questions about REST API.
A REST API lets software exchange resources and trigger actions over HTTP. Companies use it to connect web and mobile applications with databases, business services, payment providers, logistics systems and external partners.
A REST API usually exposes resource-oriented endpoints and uses established HTTP behavior, making it practical for many public and internal integrations. GraphQL offers client-controlled data queries, while SOAP provides a more formal message and contract model for specific enterprise environments.
A strong REST API specialist should understand HTTP, data modeling, authentication, databases and automated testing. OpenAPI, Docker, CI pipelines, observability and cloud gateways are also useful when the interface runs as part of a larger service landscape.
The right REST API professional depends on the project scope, risk and existing architecture rather than a fixed tenure requirement. A simple internal integration may need focused endpoint work, while a public or regulated service calls for proven judgment around security, versioning, resilience and compatibility.
Yes. REST API work is well suited to remote collaboration through repositories, API contracts, issue tracking and video reviews. Essen teams should agree early on working hours, documentation standards and whether German, English or both are needed for workshops and handovers.
Ask how the REST API professional handles resource naming, validation, status codes, errors, pagination, authentication and backward compatibility. Request a concise design example or review of an existing contract, and listen for trade-offs supported by testing and monitoring.
A REST API specialist can cover interface design and delivery, but a complete integration may also require database, frontend, cloud, security or domain expertise. Clarify ownership of deployment, data migration, monitoring and partner testing before the work begins.
Good REST API documentation explains authentication, endpoints, parameters, schemas, examples, errors and compatibility rules in one dependable contract. OpenAPI can make that information reviewable and testable, but the content still needs to match the running service.
The average hourly rate of freelancers in Essen, Germany who have used REST API in their recent projects is 84 €, which corresponds to a daily rate of about 670 € based on an 8-hour working day.
Of the freelancers in Essen, Germany who have used REST API in their recent projects, 95% hold at least a Bachelor's degree and 62% hold at least a Master's degree.
On average, freelancers in Essen, Germany who have used REST API in their recent projects have 15 years of professional experience, with a single engagement typically lasting around 1.9 years.
The most common languages among freelancers in Essen, Germany who have used REST API in their recent projects are German (100%), English (100%), and Spanish (21%).
The most common industries among freelancers in Essen, Germany who have used REST API in their recent projects are Information Technology (96%), Banking and Finance (50%), and Transportation (33%).
The most common business areas among freelancers in Essen, Germany who have used REST API in their recent projects are Information Technology (96%), Product Development (92%), and Quality Assurance (54%).
Main locations of FRATCH Experts, who have recently used REST API
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.
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