MonoDevelop is a cross platform IDE mostly aimed at Mono/.NET developers

An experimental Go cross platform UI library.

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

Go Struct and Field validation, including Cross Field and Cross Field Cross Struct validation

Cross platform xamarin and windows plugins for PCLs

A cross platform manga/doujinshi manager with tagging support

Cross Platform UI Kit powered by Blink/Chromium Content Lib

Cross Platform GUI for D programming language

Cross platform browser plugin for serial port communication from JavaScript

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.

New Cross Food Coop & Eat A Rainbow Web Application

A Simple Cross Origin Resource Sharing for Lumen Framework (5.0|5.1).

A Cross Platform 3D Renderer (DX12, Metal, Vulkan)

PromisePipe - reusable cross process promise chains

Window creational toolkit, cross platform. Written in D.

Cross platform library for smarttv

A cross platform tray monitor to trigger builds, receive the notifications from QuickBuild

Hexa is a high level, strictly typed programming language https://discord.gg/SsAWf9M

MXE (M cross environment)

Cross a pomodoro timer with your favourite task + todo + issue management software and make it all hacker friendly.

An experimental Go cross platform UI library.