Šimon Rozsíval
Software Engineer at Microsoft
Prague, Prague, Czechia
Summary
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Rockstar🎓
Top SchoolŠimon Rozsíval is a software engineer based in Prague with 12 years of experience spanning front-end, back-end, and mobile development and a strong academic foundation in artificial intelligence. Currently at Microsoft, he contributes to core .NET projects—improving Android networking, adding NTLMv2 support, and hardening certificate and hostname handling—which highlights deep platform-level debugging skills not obvious from typical app roles. His background includes full-stack and app development at companies like Toggl and Better Stack, giving him a pragmatic product-minded approach alongside system-level expertise. He has tackled tricky runtime issues in .NET MAUI and the .NET runtime to improve trimming, XAML loading, and Android test stability, demonstrating care for maintainability and cross-platform consistency. Comfortable across languages and layers, Šimon combines theoretical CS training with practical contributions to major open-source projects.
11 years of coding experience
9 years of employment as a software developer
Gymnázium ŠumperkMagistr (Mgr.), Artificial Intelligence, Magistr (Mgr.), Artificial Intelligence at Univerzita KarlovaBc., Programming and Software Systems, 3., Bc., Programming and Software Systems, 3. at Univerzita Karlova v Praze
English, Czech
Stackoverflow
35reputation
8kreached
4answers
0questions
Github Skills (19)
xaml10
maui10
net10
dotnet10
net-maui10
asp-net10
android10
dotnet-core10
csharp10
xamarin-android9
source-code-analysis9
networking8
html6
socket6
network-stream6
Programming languages (13)
Github contributions (5)
dotnet/maui
Apr 2022 - Mar 2025
.NET MAUI is the .NET Multi-platform App UI, a framework for building native device applications spanning mobile, tablet, and desktop.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:150 reviews, 88 PRs, 36 pushes in 2 years 11 months
Contributions summary:Šimon primarily contributed to fixing trimming warnings related to the .NET MAUI framework. These changes involved addressing issues in the source code, including updates to the BindablePropertyConverter and XamlParser, as well as improvements to XAML loading. The user also introduced and maintained feature flags for runtime parsing and assembly scanning. This work focused on enhancing the framework's stability and maintainability, especially concerning the trimming of code and preventing code removal.
app-platformmauimulti-platformiosmicrosoft
dotnet/android
Jan 2022 - Jan 2023
.NET for Android provides open-source bindings of the Android SDK for use with .NET managed languages such as C#
Role in this project:Back-end Developer
Back-end DeveloperContributions:59 reviews, 6 commits, 31 PRs in 11 months
Contributions summary:Šimon primarily focused on enhancing the .NET for Android project by addressing critical issues and implementing new features related to HTTP client handling within the Android environment. They deprecated the Xamarin.Android.Net.AndroidClientHandler and added NTLMv2 support. They also implemented a custom validation callback for server certificates to handle self-signed certificates and addressed issues around hostname verification during redirects.
dotnetandroidsdkcsharpxamarin
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