Curios API [2025 Update] – Minecraft Equipment Slot Library by TheIllusiveC4

The Curios API (1.21.5, 1.20.1) is a powerful and modular accessory system developed by TheIllusiveC4 that allows mod developers to easily add expandable equipment slots into Minecraft. Rather than introducing any items or gameplay changes itself, this API serves as the foundation for other mods to define and manage custom slot types such as rings, belts, amulets, or trinkets while ensuring seamless compatibility with the vanilla inventory and enchantment systems.

Built for Fabric, Forge, and NeoForge, this API has become a staple library used in dozens of popular Minecraft mods, thanks to its simplicity, flexibility, and developer-friendly design.

Features:

Modular Slot Expansion:
Allows mods to define custom equipment slots via an identifier registry (e.g., curios:ring, curios:back, etc.), each with its own design and behavior.
No Default Content:
Curios adds no slots or items by default. Only two test items are available via Creative mode for developers. Slots are generated on demand based on registered tags.
Customizable UI Slots:
Developers can define slots with:
- Custom background icons
- Variable slot sizes
- Visibility toggles (show/hide/disable on player-by-player basis)
- Full API access for adding/removing slots dynamically
Vanilla Tag Integration:
Any item can become a “curio” by tagging it in the proper .json files (data/curios/tags). Items can belong to multiple curio types at once (e.g., a ring that also counts as a trinket).
Enchantment Compatibility:
Items in curio slots retain vanilla behavior, including Mending, Curse of Binding, and other enchantment effects.
Unified GUI:
A dedicated GUI screen (default key: G) provides access to all curio-equipped slots, displaying them in one place for ease of use.
Full Developer Support:
The API exposes simple functions for creating slot behaviors, integrating custom GUIs, modifying player slot availability, and syncing across clients and servers.

Requires:

Minecraft Forge or NeoForge Installer

How to install:

How To Download & Install Mods with Minecraft Forge

How To Download & Install Fabric Mods

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Why use Curios API?

For players, the Curios API acts as the silent backbone behind many modded RPG-style inventory systems. For developers, it removes the hassle of building a custom slot system from scratch. It’s performance-friendly, highly customizable, and plays nicely with vanilla rules and other mods. Whether you’re adding wearable magic rings, storage belts, or decorative accessories, Curios gives you the tools to do it cleanly, modularly, and compatibly.

FAQs

Does Curios API add any items or gameplay features?

No. It’s a backend system meant for mod developers. Only two sample items exist in Creative mode for testing purposes.

How do other mods add Curios slots?

Mods register their desired slots using the API. For example, a mod may define a `ring` slot and tag specific items that fit that category.

Can players configure slot types or numbers?

Not directly. Slot definitions are controlled via datapacks or mod configuration files. Developers can expose config options for customization.

Is it compatible with enchantments like Mending?

Yes, all equipped items retain standard enchantment behaviors, including repair via Mending or effects from curses.

What’s the difference between this and Curios API Continuation?

This is the **original** and most widely adopted version by TheIllusiveC4. The “Continuation” version is a NeoForge-specific fork maintained separately.