ArcGIS Pro SDK - Add ins Overview
ArcGIS Pro provides a powerful framework for customizing and extending the Pro application using add-ins. The framework is similar to how ArcGIS Desktop 10.x developers have traditionally created and deployed add-ins for ArcMap. Pro add-ins are developed using the ArcGIS Pro SDK for .NET, and are developed using Microsoft Visual Studio, coding in either C# or VB.NET.
Learn more about the ArcGIS Pro SDK and developing add-ins for Pro at: http://pro.arcgis.com/en/pro-app/sdk/