The Endo-Upgrades are types of equipment sold by Mendo. They are used to upgrade the party's defense in the game. There appears to be only three of them to buy, but it's believed that Scott Cawthon will add more into the game.
- Reinforced (Cost 250) - They boost up defense by 10.
- Steel (Cost 1,500) - They boost up defense by 20.
- Titanium (Cost 9,000) - They boost up defense by 100.
Total cost to buy all the Endo-Upgrades: 10,750
- The starter Endoskeleton is Endo-01's body, and the Reinforced Endoskeleton is Endo-02's.
- The Steel Endoskeleton is Endo-01's body, just enlarged and recolored.
- Mendo himself has what appears to be a recolored Steel Endoskeleton.
- Because the player can only have one Endo-Upgrade equipped at a time, and there is no way of switching back to one endoskeleton after equipping another, it is advised that the player never purchases an Endo-Upgrade worse than what one already has.