BiggerHotbar

This mod works fully clientside!

This mod allows you to use the bottom row of your inventory as 9 extra hotbar slots. You can scroll seamlessly into your virtual second hotbar, your items are automatically swapped, but visually nothing changes.

It looks just like you're directly using the items from your inventory in your hotbar.

The mod will remember your correct item positions, so no need to worry about your inventory getting messed up when you leave or join a world/server.