This is C++ based and Blueprint frontended solution. Main feature of this solution is that you receive an inventory system where every item has dimensions. Also, you could drag, drop, throw away, pick up again and stack your items.
Also, you get:
Fast Slots with hotkey functional
Loot and Trade system
Context menu for your items.
Equipment widget and spellbook widget.
Here is a video of how it works: https://youtu.be/NqGC7H9tdQc
Number of Blueprints: 21
Number of C++ Classes: 30
Network Replicated: No
Supported Development Platforms: Windows
Supported Target Build Platforms: Windows
Documentation: Link https://gist.github.com/ks-zealot/bf0946131c52423db901ea35eb26c59d
Support : mailto:firstname.lastname@example.org
Important/Additional Notes: this solution presupposes that you will build your UI on canvas, i.e, every widget has UCanvasPanelSlot. Otherwise it doesn't work.