Arcane Backpacks

A Fabric mod for Minecraft 1.21.11 that adds tiered portable storage with upgrades, fluid/XP tanks, and deep customisation.

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Features

7 Backpack Tiers

Tier	Default Size	Upgrade Slots
Standard	3×9	1
Iron	4×9	2
Copper	4×9	2
Golden	5×9	3
Silver	5×9	3
Diamond	7×9	4
Obsidian	8×9	6

All values are configurable per-tier via the in-game ModMenu config screen.

Stack Upgrades

Six tiers of stack upgrades that multiply the maximum stack size in the backpack. Multiple upgrades stack multiplicatively.

Upgrade	Multiplier
Starter	×1.5
Tier 1	×2
Tier 2	×4
Tier 3	×8
Tier 4	×16
Omega	Unlimited (2,147,483,647)

Slots with more than 999 items display compact counts (1k, 2k, 1M, etc.). Hold Shift to reveal the exact number.

Item Filter Upgrade

Control exactly which items can enter the backpack. Configure up to 9 filter slots with Whitelist or Blacklist mode. Scope can be set to apply to all insertions or magnet pickups only.

Advanced Item Filter Upgrade offers 18 filter slots for finer-grained control.

Tank Upgrade (3 Tiers)

Adds a fluid + XP storage tank to the backpack. Three tiers with increasing capacity.

• Left-click the XP bar — deposit all player XP
• Right-click the XP bar — withdraw all XP
• Middle-click the XP bar — open custom transfer popup (supports k/M shorthand, e.g. 5k, 2.5M)
• Left/right-click water or lava bars with a bucket to fill or drain

Tank data is saved to the upgrade item when removed, so it persists across backpacks.

Refill Upgrade

Automatically tops up partial item stacks in the backpack from its own inventory on a server tick.

Quick Transfer

Shift-click a backpack in your inventory to instantly move all eligible items from your inventory into it. Respects the Item Filter if one is installed.

Backpack Preview

Hover over a backpack in your inventory to preview its contents as a compact grid. Hold F3+H for a full itemised list.

Customisation

• Custom name — click the backpack name in the GUI to rename. Supports & colour codes (e.g. &bMy Backpack).
• Custom icon — assign any item as the backpack's display icon.
• Bag-in-bag — store backpacks inside backpacks (configurable, loop-protected).

Placement

Right-click to place a backpack as a block in the world. It functions identically to the item — upgrades, tank, and inventory all work in placed form.

Trinkets Integration

Backpacks can be equipped in the Back slot via the Trinkets mod. All features (renaming, tank interaction, stack upgrades) work correctly from the trinket slot.

Keep on Death

Optionally keep backpacks on death — works for both inventory and Trinkets slot (configurable).

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Config (ModMenu)

Open the config screen via ModMenu → Arcane Backpacks. Per-tier settings:

• Enable/disable each tier
• Rows and columns
• Upgrade slot count

Global settings: Allow Bag in Bag, Keep on Death, Can Burn.

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Requirements

Dependency	Version
Minecraft	1.21.11
Fabric Loader	≥ 0.18.0
Fabric API	≥ 0.140.0
Java	21

Optional: Trinkets 3.11.0+, ModMenu

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Installation

1. Install Fabric Loader for Minecraft 1.21.11
2. Download Fabric API
3. Drop arcanebackpacks-1.1.0-fabric-mc1.21.11.jar into your mods/ folder
4. Launch the game

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Building from Source

git clone https://github.com/Abytzu/arcane-backpacks
cd arcane-backpacks
gradlew build

Output JAR will be in build/libs/.

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License

MIT — see LICENSE

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Links

• Modrinth
• Issues