Ingo (Dipl.-Inform.) Grebe
Founder and Owner
Experience
Development of practice management software for appointments, including online booking
Reactive Systems
For a specialized diabetes center in Hamburg, I designed and independently implemented a custom practice software. The goal was to develop a fully integrated solution for managing appointments, patients, and practitioners – including online booking for patients.
Tasks and responsibilities:
- Architecture, design, and complete development of the web application
- Implementation of the user interface with Angular, SCSS, and Bootstrap
- Development of the backend with ASP.NET Core, REST APIs, and MS SQL
- Implementation of a role-based user concept for parallel use by medical staff
- Integration of an online booking system for patients
- Conducting all tests and close coordination with medical staff
- Agile approach using Scrum, including iterative planning and direct requirement clarification with doctors and staff
Results and impact:
- The software is used daily by up to 10 staff members at the same time and has noticeably simplified the practice's appointment management
- Patient online booking was successfully established and is used regularly
- The application impresses with intuitive usability and reliable performance
- High satisfaction from the practice management and team due to a practical, tailor-made implementation
Further development of a web application for vehicle inspections
GTÜ - Gesellschaft für Technische Überwachung
As part of a long-term project at GTÜ (Gesellschaft für Technische Überwachung mbH), I am involved as a full-stack developer in the further development of a modern web application that digitally supports vehicle inspections such as general inspections (HU) or safety tests (SP). The application is a core part of the company's newest software generation and is used nationwide.
Tasks and responsibilities:
- Implementation of new features on the frontend and backend with Angular and ASP.NET Core
- Identification and resolution of performance issues on the server side
- Development and optimization of logging mechanisms for improved traceability and error analysis
- Continuous refactoring of legacy code to ensure long-term maintainability
- Participation in architecture decisions and technical evolution of the overall system
- Close collaboration with QA, DevOps, and other development teams in an agile environment (Scrum/Kanban mix)
Results and impact:
- Active contribution to resolving critical performance issues in the backend as part of the performance team
- High customer satisfaction through fast and reliable implementation of new requirements
- Continuous onboarding into complex system parts and stable delivery of high-quality code
PWA for time tracking and CMS for managing employees and time entries
Reactive Systems
For a construction company from Wetzlar, I planned and fully developed a progressive web app (PWA) for mobile time tracking and a web-based CMS for managing employees, job sites, and time entries. The goal was to provide a user-friendly solution that works reliably in both online and offline modes.
Tasks and responsibilities:
- Architecture, design, and full implementation of the application
- Frontend development with Angular and SCSS with special focus on offline capabilities
- Backend implementation with ASP.NET Core, Entity Framework Core, and MS SQL
- Building a CMS for managing employees, job sites, and time entries
- Integration of a synchronization logic for offline use of the PWA
- Close coordination with the owner and staff for practical implementation
- Iterative approach using Scrum with regular feedback and direct testing in day-to-day operations
Results and impact:
- Over 40 employees use the app daily on job sites even without an active internet connection
- The software was easily adopted by all employees due to its intuitive usability
- The owner was extremely satisfied with the quick implementation and precise functionality of the solution
- The application sustainably digitalized and simplified time management in the company
Mobile app for conducting and logging COVID-19 antigen rapid tests
Reactive Systems
- Technologies: Angular, Bootstrap, HTML, NativeScript, SCSS, TypeScript
Further development of a web application for submitting medical invoices
Reactive Systems
- Technologies: AngularJS, Bootstrap, CSS, HTML, Java, JavaScript, SCSS
Web application for creating and publishing ad campaigns
Reactive Systems
- Technologies: Angular 5, ASP.NET, Facebook API, Google APIs, HTML, JavaScript, C#
Further development of a web application for submitting doctor invoices
Reactive Systems
- Technologies: AngularJS, Bootstrap, CSS, HTML, JavaScript, SCSS
Development of website, API, and database for real estate presentation
Reactive Systems
- Technologies: Angular 4, ASP.NET Core, Bootstrap, C#, Entity Framework Core
Further development of software for reward shops
Reactive Systems
- Technologies: AngularJs, ASP.NET WebAPI, C#, CSS, HTML, JS, Entity Framework, SQL
Development of software for particle measurement in cleanrooms
Reactive Systems
For an engineering firm in Langen, I developed custom software that digitally maps the entire process of particle measurement in cleanrooms – from managing measurement tasks, rooms, and limit values to mobile execution and post-processing of measurements. The application supports both office and field use and was specifically tailored to cleanroom technology requirements.
Tasks and Responsibilities:
- Planning and full implementation of the application including architecture design
- Development of a back office system with ASP.NET MVC and Entity Framework
- Implementation of the user interface with AngularJS, Bootstrap, and classic web technologies (HTML, JS)
- Implementation of the mobile app for offline execution of particle measurements on site
- Development of synchronization logic to transfer measurement data to the central server
- Close collaboration with the owner and technical staff for continuous optimization
- Agile approach following Scrum with iterative deliveries and practical validation
Achievements and Impact:
- Daily use of the software by over 10 employees – both in the field and in the office
- Offline functionality enables reliable execution of measurements directly at the customer
- The application was quickly adopted by the entire team due to its intuitive operation
- Significant improvement in efficiency and data quality in particle measurement and post-processing
Development of facial recognition software
Reactive Systems
- Technologies: AngularJs, ASP.NET WebAPI, C#, CSS, HTML, JS, Neurotechnology SDK, WCF
Further development of a geographic information system
Reactive Systems
- Technologies: Angular, ASP.NET WebAPI, HTML, JavaScript, Material Design, SCSS
Development of a reporting system
Reactive Systems
- Technologies: ASP.NET, C#, SQL Reporting Services
Industries Experience
See where this freelancer has spent most of their professional time. Longer bars indicate deeper hands-on experience, while shorter ones reflect targeted or project-based work.
Experienced in Information Technology (5 years), Healthcare (4 years), Professional Services (3 years), Automotive (2.5 years), Construction (1 year), and Advertising (1 year).
Business Areas Experience
The graph below provides a cumulative view of the freelancer's experience across multiple business areas, calculated from completed and active engagements. It highlights the areas where the freelancer has most frequently contributed to planning, execution, and delivery of business outcomes.
Experienced in Information Technology (10.5 years), Product Development (5.5 years), Marketing (1 year), Accounting (1 year), and Business Intelligence (1 year).
Summary
Since 2007 I have been working with great passion as a software developer and software architect in desktop and web development. As a consultant I help improve the quality of my clients' software. My specialty is developing web-based business applications. I build backends in C# using the Microsoft .NET Framework as services or APIs. They usually run in the cloud and on local intranets. The frontends are developed in JavaScript/TypeScript, HTML and (S)CSS with Angular and can be used on browser-capable systems. My strengths lie in independent and responsible thinking and acting.
Since 2007 I have been working with passion as a software developer and software architect in desktop and web development. As a consultant I increase the quality of my clients' software. By founding Reactive Systems I aim to take responsibility for larger projects and support junior developers.
Skills
- Angular And Angularjs
- Asp.net Core
- Asp.net Mvc And Webapi
- Bootstrap
- Entity Framework
- Jquery
- Nativescript
- Wcf
- Winforms And Wpf
- C#
- Fdo
- Javascript
- Html
- Razor
- (S)css
- Sql
- Sql Server
- Sql Reporting Services
- Typescript
- Azure Devops
- Git
- Jira
- Npm And Nodejs
- Team Foundation Services
- Visual Studio
- Webstorm
Languages
Education
Diploma in Computer Science · Computer Science
Profile
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