MonoDevelop is a cross platform IDE mostly aimed at Mono/.NET developers
Cross platform parser for the Gherkin language. Used by Cucumber to parse .feature files.
Cross platform GUI framework for desktop and mobile applications in .NET
A cross platform manga/doujinshi manager with tagging support
Go Struct and Field validation, including Cross Field and Cross Field Cross Struct validation
Bread Player, a free and open source music player powered by UWP and C#/.NET with a sleek and polished design built for, and by, the people seeking a better alternative to Groove and Windows Media Player by Microsoft.
A Simple Cross Origin Resource Sharing for Lumen Framework (5.0|5.1).
PromisePipe - reusable cross process promise chains
A cross platform tray monitor to trigger builds, receive the notifications from QuickBuild
Cross a pomodoro timer with your favourite task + todo + issue management software and make it all hacker friendly.