WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle. 

EasyCompressor is an open-source compression abstraction library that supports and implements many compression algorithms such as Zstd, LZMA, LZ4, Snappy, Brotli, GZip and Deflate. It is very useful for using along with Distributed Caching or storing files in database. 

I am so excited about using Plotly packages in Power BI.

So What is Plotly: is an R package for creating interactive web-based graphs via the open source JavaScript graphing library :https://plot.ly/r/getting-started/ 

One SQL unit testing framework which I have been using lately is tSQLt, which is a simple open-source framework. 

- TimeSeries.Guru is a column-oriented Time Series Database as a Service
- MonetDB is an Open Source column-oriented database
- Wikipedia 

This release will be shortly followed by R Tools 1.0 for Visual Studio 2017 in early May. RTVS is a free and open source plug-in that turns Visual Studio into a powerful and productive R development environment. 

The .NET Core and the Core Libraries are open source and run on Windows, Mac, and Linux. In fact, you can run them with support, today, in production on Windows and Linux (Mac is for development, not production). 

WpfDesigner is a set of Assemblies which can be included in your Project to implement a XAML GUI Editor. 

This is a set of NuGet packages that makes your Blazor apps display the source .razor file name that generated the HTML element under the mouse cursor when entering the Ctrl + Shift + F hotkeys.