Download Drag & Drop Pro FREE Unity. 

Customizable plugin to make your own drag and drop system.
Implement your game UI, inventories, etc by using Drag & Drop Pro plugin.

All kinds of Unity UI elements can be used as an object or a panel.

Features :

– Full C# source code.

– Easy setup and well-written documentation.

– Mobile supported.

– Save system.

– More than 10 customization tools : Look at the screenshots please.

– Filter panels tool : To specify that which objects can drop on which panels.

– Multi Object tool : Allow to drop more than one object on a panel.

– Panel Object detection : To know which object is on the target panel.