Cloud Boots allow you to jump 5 blocks high and take no fall damage. The boots durability is not reduced by wearing them, jumping and falling. Being injured in combat does reduce the boots durability and they will eventually break. You may want to unequip your Cloud Boots before going into combat, so that they last longer.
These can be traded for with NPCs, show up rarely in dungeon chests, and are dropped by Neptune.
Although Chocolate Quest is not updated to 1.12 as of yet, Tiviacz1337 has created a 1.12.2 mod that adds in the cloud boots and Golden Feathers used to craft them as a standalone item. You can find it here.
Chocolate Quest Cloud Boots