Recommended and mentioned products
The Roslyn .NET compiler provides C# and Visual Basic languages with rich code analysis APIs. - dotnet/roslyn
A better date and time API for .NET. Contribute to nodatime/nodatime development by creating an account on GitHub.
For some at least slightly smaller and less intimidating codebases, try for example https://github.com/nodatime/nodatime/ https://github.com/DapperLib/Dapper.