Ingo Grebe - Founder and Owner

Q: Where is Ingo based?

Ingo is based in Wetzlar, Germany and can operate in on-site , hybrid , and remote work models.

Q: What languages does Ingo speak?

Ingo speaks the following languages: German (Advanced), English (Advanced) .

Q: How many years of experience does Ingo have?

Ingo has at least 10 years of experience. During this time, Ingo has worked in at least 13 different roles and for 2 different companies . The average length of individual experience is 1 year and 10 months . Note that Ingo may not have shared all experience and actually has more experience.

Q: What is Ingo's latest experience?

Ingo's most recent position is Development of practice management software for appointments, including online booking at Reactive Systems .

Q: What companies has Ingo worked for in recent years?

In recent years, Ingo has worked for Reactive Systems and GTÜ - Gesellschaft für Technische Überwachung .

Q: Which industries is Ingo most experienced in?

Ingo is most experienced in industries like Information Technology , Healthcare , and Professional Services . Ingo also has some experience in Automotive , Advertising , and Real Estate .

Q: Which business areas is Ingo most experienced in?

Ingo is most experienced in business areas like Information Technology , Product Development , and Marketing . Ingo also has some experience in Accounting and Business Intelligence .

Q: Which industries has Ingo worked in recently?

Ingo has recently worked in industries like Automotive , Healthcare , and Information Technology .

Q: Which business areas has Ingo worked in recently?

Ingo has recently worked in business areas like Information Technology and Product Development .

Recommended expert

Wetzlar, Germany

Experience

Jan 2024 - Dec 2024

1 year

Hamburg, Germany

Remote

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

Jun 2023 - Present

2 years 10 months

Stuttgart, Germany

Remote

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

Feb 2022 - Dec 2022

11 months

Wetzlar, Germany

Remote

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

Jan 2021 - Dec 2021

1 year

Mobile app for conducting and logging COVID-19 antigen rapid tests

Reactive Systems

Technologies: Angular, Bootstrap, HTML, NativeScript, SCSS, TypeScript

Jan 2020 - Dec 2020

1 year

Further development of a web application for submitting medical invoices

Reactive Systems

Technologies: AngularJS, Bootstrap, CSS, HTML, Java, JavaScript, SCSS

Jan 2018 - Dec 2018

1 year

Web application for creating and publishing ad campaigns

Reactive Systems

Technologies: Angular 5, ASP.NET, Facebook API, Google APIs, HTML, JavaScript, C#

Jan 2018 - Dec 2018

1 year

Further development of a web application for submitting doctor invoices

Reactive Systems

Technologies: AngularJS, Bootstrap, CSS, HTML, JavaScript, SCSS

Jan 2017 - Dec 2017

1 year

Development of website, API, and database for real estate presentation

Reactive Systems

Technologies: Angular 4, ASP.NET Core, Bootstrap, C#, Entity Framework Core

Jan 2017 - Dec 2017

1 year

Further development of software for reward shops

Reactive Systems

Technologies: AngularJs, ASP.NET WebAPI, C#, CSS, HTML, JS, Entity Framework, SQL

Jan 2016 - Dec 2018

3 years

Langen, Germany

Hybrid

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

Jan 2016 - Dec 2016

1 year

Development of facial recognition software

Reactive Systems

Technologies: AngularJs, ASP.NET WebAPI, C#, CSS, HTML, JS, Neurotechnology SDK, WCF

Jan 2015 - Dec 2015

1 year

Further development of a geographic information system

Reactive Systems

Technologies: Angular, ASP.NET WebAPI, HTML, JavaScript, Material Design, SCSS

Jan 2014 - Dec 2014

1 year

Development of a reporting system

Reactive Systems

Technologies: ASP.NET, C#, SQL Reporting Services

Industry Experience

See where this freelancer has spent most of their professional time.

Experienced in Information Technology, Healthcare, Automotive, Professional Services, Construction, and Advertising.

Information Technology

Healthcare

Automotive

Professional Services

Construction

Advertising

Business Area Experience

See which departments and functions this freelancer has contributed to most.

Experienced in Information Technology, Product Development, Marketing, Accounting, and Business Intelligence.

Information Technology

Product Development

Marketing

Accounting

Business Intelligence

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

German

Advanced

English

Advanced

Education

Diploma in Computer Science · Computer Science

Statistics

Experience

Total positions 13

Experience in Information Technology 5 y

Avg length 1 y 2 m

Longest experience 2 y 11 m

Global Experience

Countries worked in 1 (Germany)

Primary country Germany

Expertise

Recent roles Development of practice management software for appointments, including online booking, Further development of a web application for vehicle inspections, PWA for time tracking and CMS for managing employees and time entries

Main industries Information Technology, Healthcare, Automotive

Main business areas Information Technology, Product Development, Marketing

Profile

Created

July 2025

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Frequently asked questions

Do you have questions? Here you can find further information.

Where is Ingo based?

Ingo is based in Wetzlar, Germany and can operate in on-site, hybrid, and remote work models.

What languages does Ingo speak?

Ingo speaks the following languages: German (Advanced), English (Advanced).

How many years of experience does Ingo have?

Ingo has at least 10 years of experience. During this time, Ingo has worked in at least 13 different roles and for 2 different companies. The average length of individual experience is 1 year and 10 months. Note that Ingo may not have shared all experience and actually has more experience.

What roles would Ingo be best suited for?

Based on recent experience, Ingo would be well-suited for roles such as: Development of practice management software for appointments, including online booking, Further development of a web application for vehicle inspections, PWA for time tracking and CMS for managing employees and time entries.

What is Ingo's latest experience?

Ingo's most recent position is Development of practice management software for appointments, including online booking at Reactive Systems.

What companies has Ingo worked for in recent years?

In recent years, Ingo has worked for Reactive Systems and GTÜ - Gesellschaft für Technische Überwachung.

Which industries is Ingo most experienced in?

Ingo is most experienced in industries like Information Technology, Healthcare, and Professional Services. Ingo also has some experience in Automotive, Advertising, and Real Estate.

Which business areas is Ingo most experienced in?

Ingo is most experienced in business areas like Information Technology, Product Development, and Marketing. Ingo also has some experience in Accounting and Business Intelligence.

Which industries has Ingo worked in recently?

Ingo has recently worked in industries like Automotive, Healthcare, and Information Technology.

Which business areas has Ingo worked in recently?

Ingo has recently worked in business areas like Information Technology and Product Development.

What is Ingo's education?

Ingo attended education in Computer Science.

What is the availability of Ingo?

Ingo is immediately available full-time for suitable projects.

What is the rate of Ingo?

Ingo's rate depends on the specific project requirements. Please use the Meet button on the profile to schedule a meeting and discuss the details.

How to hire Ingo?

To hire Ingo, click the Meet button on the profile to request a meeting and discuss your project needs.

Average rates for similar positions

Rates are based on recent contracts and do not include FRATCH margin.

1200

900

600

300

Market avg: 900-1060 €

The rates shown represent the typical market range for freelancers in this position based on recent contracts on our platform.

Actual rates may vary depending on seniority level, experience, skill specialization, project complexity, and engagement length.

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