Top 20 NuGet add-in Packages

Extensibility library.
Kraken is a set of open source libraries for SharePoint development. The package includes code for writing provider hosted apps, including CSOM utilities.
A .NET Core Global Tool for hosting Microsoft Office Add-ins during development
Serilog logging wrapper for Add-in X
Visual Studio Extensions development SDK
The power of XAML Styler wrapped up in a small executable that can be integrated into build scripts, git commit templates, and more. This package is built on top of the same styling engine that powers the Visual Studio plugin, and can be configured by specifying an external configuration.
CSOM extensions to send SMS to Single or Multiple users of your SharePoint Online Site. Select user(s) by SharePoint Group or Username/Email or SharePoint User Object or SharePoint FieldUserValue(Person or Group column value(s)). Utilizes SharePoint Add-in: SMS Gateway Connector (SMS Via SharePoint ...
CSOM extensions to send SMS to Single or Multiple users of your SharePoint Online Site. Select user(s) by SharePoint Group or Username/Email or SharePoint User Object or SharePoint FieldUserValue(Person or Group column value(s)). Utilizes SharePoint Add-in: SMS Gateway Connector (SMS Via SharePoint ...
Log4Net logging wrapper for Add-in X.
Wrapper for the inversion of control container Autofac - Add-in X
Implementation for the WPF helper for Excel-DNA - Add-in X
This add-in gives you your own dashboard with items you recently worked on in your Visual studio editor. Provides a Quick and handy way to navigate to these items and manage them. It is applicable to code files, TFS tasks, etc. Recently Used Files is supported for Visual Studio 2010 and 2012.
Open-source Excel add-in in C#/.NET4.0 that makes matrix, vector and most importantly, table-valued functions of Finaquant Calcs available for Excel users and programmers. Based on ExcelDNA and NetOffice
Interface that will be used for the logging wrapper used by Add-in X
Interface for the wrapper of inversion of control - Add-in X
Interface for the WPF helper method - Add-in X
Implementation of the fluent ribbon buider for Excel Add-in. We recommend to add the AddinX.Ribbon.ExcelDna package to use the fluent ribbon with Excel-DNA.
Fluent ribbon builder for Excel-DNA. It simplifies the creation of the ribbon with Excel-DNA so you don't have to write XML or to create the callback methods.
A library that provides simplified threaded and non-threaded execution of SQL statements. It can be used to expose an interface to Microsoft Excel clients, providing threaded, async operations to a single-thread application.
Wrapper for the ConfigurationManager class - Contract - Add-in X