Karl Steinzer, Developer in Horitschon, Austria
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Karl Steinzer

Verified Expert  in Engineering

Windows Communication Foundation (WCF) Developer

Horitschon, Austria
Toptal Member Since
February 22, 2021

With a BS in software development and 15 years of experience in complex software projects ranging from small startups to international companies, Karl is able to quickly contribute to development teams. He enjoys working in multi-cultural and distributed teams and is eager to improve his technical skills. Because of his passion for software development, he strives to deliver high-quality work and to exceed the expectations of customers and users.


C#.NET, .NET Core, Git, REST APIs, XAML, Windows Presentation Foundation (WPF)
JetTicket Software GmbH
C#.NET, Payment APIs, Windows Communication Foundation (WCF), VB.NET
Social Media Integration, Azure, Windows Phone 8, Microsoft Silverlight, C#.NET




Preferred Environment

Visual Studio .NET, Git, Microsoft Team Foundation Server, .NET Core, C#.NET

The most amazing...

...project i've worked on was an object annotation app for a German automotive company with people from multiple countries pushing autonomous driving forward.

Work Experience

Senior Full-stack Developer

2017 - PRESENT
  • Developed a WPF application for object annotation with 12 parallel views of 2D camera images and 3D point clouds.
  • Optimized code to handle a huge amount of data with HDF as a data source and SQLite as a local client database.
  • Acted as the lead developer in an international team with up to 15 members distributed in Germany, Austria, India, and Russia.
  • Created an implementation in .NET Core to connect RFID readers and payment terminals to a custom vending platform.
Technologies: C#.NET, .NET Core, Git, REST APIs, XAML, Windows Presentation Foundation (WPF)

Senior Full-stack Developer

2014 - 2016
JetTicket Software GmbH
  • Developed and refactored a custom template based webshop including migration from older versions.
  • Created an update tool to improve the webshop update process in terms of required time and error prevention.
  • Created the prototype of a WCF service to act as a middleware to a legacy system.
Technologies: C#.NET, Payment APIs, Windows Communication Foundation (WCF), VB.NET

Senior Full-stack Developer

2010 - 2013
  • Developed a CMS using MS Silverlight and front ends including social media integration (Facebook, Twitter, and Google+).
  • Implemented unit tests and automated web tests using the Telerik framework.
  • Created the concept for an eNegotation platform and served as the team lead of an Egyptian development team.
Technologies: Social Media Integration, Azure, Windows Phone 8, Microsoft Silverlight, C#.NET

Full-stack Developer

2006 - 2009
  • Created an eSourcing solution for auctions and tenders hosted on Microsoft IIS and SQL Server.
  • Integrated Excel for online and offline editing and calculation.
  • Implemented, tested, and deployed the solution including monitoring and support.
Technologies: C#.NET, IIS 7, SQL Server 2010, Ajax, HTML, JavaScript, ASP.NET


A WPF application using SQLite as a local database for object annotation to label image, video, and point cloud data used for autonomous driving. As additional data sources, HDF containers were used as well as a REST-API to communicate with other systems. To project data from 3D point cloud to 2D images a sync mechanism was implemented to support users at labeling complex scenes. Additionally, a plugin architecture using MEF was used to make the application extensible with different drawing and import/export plugins.


An ASP.NET application hosted on IIS and using SQL Server as a database to handle auctions and tenders with different rating algorithms. JavaScript and Ajax were used to improve usability and response times.

An Excel template engine was implemented to allow online and offline spreadsheet calculation and editing as well as import/export.

As a reporting framework, Telerik was used and export to PDF of online data was provided.
2005 - 2020

Bachelor's Degree in Software and Information Engineering

Technical University of Vienna - Vienna, Austria


REST APIs, HDF5, Entity Framework


Visual Studio .NET, Microsoft Team Foundation Server, Git, Microsoft Silverlight, Telerik Reports


C#.NET, SQL, JavaScript, VB.NET, XAML, HTML, C++/CLI


.NET Core, ASP.NET, Windows Presentation Foundation (WPF)


Dependency Injection, Inversion of Control


SQLite, JSON, SQL Server 2010, Microsoft SQL Server


Windows Phone 8, Azure, Telerik WPF


Windows Communication Foundation (WCF), Ajax, IIS 7, Social Media Integration, Payment APIs, IIS

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