REST API Experts in Essen
to connect systems with vetted, available freelancers matched in minutesHire experts who design reliable REST endpoints, integrate platforms with OAuth and OpenAPI, and improve API performance, security and documentation. FRATCH matches you quickly with precise, vetted and available freelancers for your project.
Meet FRATCH Experts in Essen, who have recently used REST API
Fadi S.
Last position:
Data Scientist at E-Commerce
- Designed and developed a production-ready data platform based on Microsoft Fabric for an e-commerce company
- Built a scalable Medallion Architecture (Bronze, Silver, Gold) with Lakehouse and Delta Lake as the foundation for analytics and AI applications
- Developed a metadata-driven ETL platform with PySpark and a generic Incremental Loading Framework (SQL Server → Bronze → Silver → Gold)
- Developed reusable components for Microsoft Fabric Notebooks to standardize data integration, transformation, and validation
- Implemented automated data pipelines including monitoring, logging, error handling, and Delta MERGE strategies for stable production operations
- Built a business layer architecture for reporting, data warehousing, and reusable data products
- Integrated heterogeneous data sources via SQL Server, REST APIs, Amazon SP API, and Google Analytics 4
- Worked closely with business departments to analyze business requirements and translate them into scalable data architectures
Technologies: Microsoft Fabric, PySpark, Python, SQL Server, Delta Lake, Lakehouse, OneLake, Data Factory, Data Warehouse, REST APIs, Amazon SP-API, Google Analytics 4
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.
Dennis G.
Last position:
AI & Automation Consultant at Flow10x
- AI consulting for HR & recruiting (identification and implementation of AI potential throughout the candidate journey)
- Development and implementation of AI-supported recruiting systems
- Building automations to optimize hiring processes (screening, communication, follow-ups)
- Design and integration of chatbots & AI assistants for candidate communication
- Analysis and optimization of existing HR processes with a focus on efficiency, time-to-hire & candidate experience
- Development of custom software solutions for recruiting workflows
- Integration of AI systems into existing HR tools & infrastructures
- Focus on scalability, automation, and measurable impact
- Advising companies on digital transformation in HR
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.
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 repositories
- 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 a UX design with Power Apps
Celil U.
Last position:
ZÜRS Geo 2021 at adesso SE
- Frontend development
- Spring Boot
- Swagger
- Git
- GitLab
- SonarQube
- Docker
- Maven
- Java
- Angular
Sileem H.
Last position:
Senior Consultant, Lead-Developer, Architect at Bundesamt für Informatik und Telekommunikation
- Company FROX (Schweiz), end customer: Bundesamt für Informatik und Telekommunikation.
- Consulting and development. ITSM Suite, development of a semi-generic REST API interface solution. Performance tuning.
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
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
2 years (Germany: 2.9 years)
Positions per freelancer
9 (Germany: 12)
Top business areas
Information Technology, Product Development, Quality Assurance
Top industries
Information Technology, Banking and Finance, Professional Services
Certification focus areas
Information Technology, Project Management, Product Development
Bachelor's degree or higher
95% (Germany: 92%)
Master's degree or higher
64% (Germany: 55%)
Certifications per freelancer
2 (Germany: 3)
Most common languages
German, English, French
Speak two or more languages
100% (Germany: 97%)
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 Essen 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 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 29 Oct 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 (92%)
- Banking and Finance (46%)
- Professional Services (35%)
- Automotive (31%)
- Manufacturing (31%)
- Education (27%)
- Energy (27%)
- Transportation (27%)
Please note that freelancers can work across multiple industries, so percentages overlap.
About the technology
What REST APIs do
REST APIs are web interfaces that let applications exchange resources over HTTP. They use familiar methods such as GET, POST, PUT and DELETE, usually return JSON, and keep requests stateless. Companies use them to connect frontends, mobile apps, internal services and external partners.
Where they are used
REST API specialists deliver integrations and service interfaces for many business systems:
- Connect web and mobile applications to backend services
- Expose customer, product, order and payment data
- Link CRM, ERP, logistics and identity systems
- Support partner, marketplace and third-party integrations
- Modernize legacy interfaces without replacing every system
REST APIs run across retail, manufacturing, logistics, finance, healthcare and public services. In Essen and the surrounding Ruhr region, they can support connected operations, industrial workflows and customer-facing digital products.
Ecosystem and tooling
Strong professionals work with HTTP semantics, JSON, XML where required, authentication and authorization. Their toolkit may include OpenAPI and Swagger for contracts and documentation, Postman for testing, gateways for traffic control, and tools such as Docker and Kubernetes for deployment. They also connect REST services to databases, message brokers and cloud infrastructure.
When companies need help
Freelance expertise is useful when an API must be designed, stabilized or integrated under delivery pressure:
- Define resource models, routes, status codes and error responses
- Document and version an API contract
- Secure endpoints with OAuth 2.0, JWT or API keys
- Diagnose slow requests, failures and inconsistent data
- Add automated contract, integration and load tests
A specialist can also review an existing interface before a product launch or help an internal team establish standards that remain practical as services grow.
What quality looks like
Reliable REST API work starts with clear contracts and predictable behavior. Experienced professionals consider idempotency, pagination, filtering, validation, rate limiting, observability and backward compatibility instead of treating endpoints as isolated code. They protect sensitive data, handle failures explicitly and explain decisions to frontend, backend and product stakeholders.
Working with an expert
Remote collaboration works well when repositories, API specifications, test environments and ownership are organized. On-site work in Essen may help when the API connects to factory systems, local infrastructure or teams that need close coordination; remote delivery can still work with secure access and clear communication. Assess specialists through relevant integration examples, readable documentation, test coverage, security awareness and a practical review of your existing API.
Frequently asked questions
Before you brief your next project: the most common questions about REST API.
A REST API lets software exchange data and trigger actions over HTTP. Companies use it to connect websites, mobile applications, internal services, databases and external partners through defined resources and predictable requests.
REST API design uses resource-based URLs and standard HTTP behavior, which makes it widely understood and easy to integrate. GraphQL gives clients more control over the data they request, while SOAP offers stricter contracts and established enterprise features; the right choice depends on compatibility, governance and data needs.
A strong REST API specialist usually understands backend programming, SQL or NoSQL data stores, authentication, cloud deployment and automated testing. Knowledge of OpenAPI, Swagger, Postman, Docker, API gateways and observability is also valuable.
The required experience depends on the API’s risk, integrations and traffic rather than its label alone. A straightforward internal interface may need focused implementation skills, while a public or regulated API calls for proven security, versioning, monitoring and migration experience.
Yes, REST API work is often well suited to remote collaboration because specifications, repositories and test environments are digital. For projects involving industrial equipment or protected internal systems in Essen, occasional on-site coordination may make access and operational decisions easier.
Review how the REST API specialist handles contracts, validation, error responses, authentication, testing and backward compatibility. Ask for examples of documentation and integration work, then use a small technical discussion to assess trade-offs rather than judging endpoint code alone.
An REST API may need redesign when clients receive inconsistent responses, releases break existing consumers, security controls are unclear or the interface no longer reflects the domain. A careful assessment should separate contract problems from implementation or infrastructure issues before changes begin.
Before working on a REST API, clarify its consumers, ownership, data sensitivity, authentication model, deployment path and release process. Also confirm the API contract, test data, environments, monitoring expectations and how breaking changes will be communicated.
The average hourly rate of freelancers in Essen, Germany who have used REST API in their recent projects is 85 €, which corresponds to a daily rate of about 681 € 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 64% 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 2 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 French (23%).
The most common industries among freelancers in Essen, Germany who have used REST API in their recent projects are Information Technology (92%), Banking and Finance (46%), and Professional Services (35%).
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 (50%).
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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