McStack

McStack allows you to customize the maximum stack size of any item in Minecraft - including items that normally only stack to 1, like water bottles, potions, ender pearls, and more.

Unlike vanilla behavior, McStack makes it possible to:

• Stack items like potion, splash_potion, and honey_bottle up to your own configured limits
• Shift-click to auto-stack and organize efficiently
• Double-click to collect matching items from your inventory
• Visually show clients the new stack limits (with ProtocolLib support)

Whether you're running a survival server or a custom minigame, McStack makes inventory management smarter and more flexible.

Custom stack sizes per item via config.yml
Full support for potion variants (e.g. potion:water, potion:instant_heal)
In-game commands to reload or update stack sizes
Smart stacking behavior for shift-click and double-click
ProtocolLib support to update client visuals
Works out-of-the-box with Paper 1.21.3+

Example of config.yml

stack-sizes:
  potion: 8
  potion:water: 16
  splash_potion:instant_heal: 4
  honey_bottle: 8
  ender_pearl: 16

Commands
/mcstack reload | Reloads the plugin config.
/mcstack set <item>[:variant] <amount> | Sets max stack size for an item.
/mcstack list | Lists all configured stack overrides.

Permissions
mcstack.admin | Allows use of all McStack commands.

Tips
Using ProtocolLib is recommended for best experience - it lets clients see your custom stack sizes.

Items like POTION, SPLASH_POTION, and LINGERING_POTION support specific types using the :<variant> syntax.