AltCore
by Altarmo
AltCore replaces the default player inventory with a custom screen, adds accessory slots and backpacks, and overhauls many container screens for Forge 1.20.1.
What it does
AltCore reimagines inventory and container interfaces so they are more adaptable and visually expressive, without requiring a texture pack. Its custom inventory screen replaces the default one, and an accessory system adds extra slots for worn items. Backpacks expand the storage a player carries, and the mod overhauls many utility screens through a unified GUI system that still supports standard Minecraft screens.
Interface customization is built in. Built-in style presets are available, and players can create their own. Spacing, sizes, positions and the overall look can be configured, and windows can be moved within the screen. The mod is published only for Forge, for 1.20.1, and it is licensed under the Creative Commons Attribution Non Commercial No Derivatives 4.0 license, so it is not open source. Both the server and every player need it, and the latest file is 0.3Alpha, dated 2026-07-03.
Key features
Custom player inventory
A new player inventory screen replaces the default layout, with its slots and panels rearranged.
Accessory slots
An accessory system adds extra slots beyond the vanilla armor and offhand positions.
Expandable backpacks
Backpacks add storage capacity for items the player carries.
Style presets
Built-in presets change the look of the interface, and custom presets can be made from spacing, sizes and positions.
Movable windows
Windows can be moved within a screen, so players arrange container panels to suit their layout.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Who it’s for: Players who want a larger or reorganized inventory screen on Forge 1.20.1, and server owners who want accessory slots and backpacks for their players.
How it compares
InvConfig is open source under the MIT License and also runs on client and server for 1.20.1, but it focuses on configuring existing inventory behavior rather than adding new slots. SlotZero is not open source and is also client and server for 1.20.1, adding extra slots in the same environment. G's Backpacks and Curios Containers are both all rights reserved and client and server for 1.20.1, and they add backpacks or curio-style containers that AltCore does not provide as separate mods.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| AltCore | Forge | 1.20.1 | Client and server | 2026-07-03 |
| InvConfig | Forge | 1.20.1 | Client and server | 2026-05-04 |
| SlotZero | Forge | 1.20.1 | Client and server | 2026-06-13 |
| G's Backpacks | Forge | 1.20.1 | Client and server | 2024-07-21 |
| Curios Containers | Forge | 1.20.1 | Client and server | 2024-05-14 |
Questions
Does AltCore need a texture pack?
Does AltCore have to be installed on the server?
Which Minecraft version does AltCore support?
Do AltCore's container overhauls work with other mods?
In the catalog
AltCore is one of 3,514 Library mods on ModsFinder, and one of 1,576 Library mods for Forge. 34,764 mods support Minecraft 1.20.1.
Similar mods
What the author says
AltCore adds a custom player inventory screen, accessory slots, and backpacks whose slots are added to the player inventory. In addition, the mod overhauls many vanilla screens into a unified Universal GUI system with support for style presets, configurable spacing, sizes, positions, and the overall look of the…
Official listing
- Modrinth page
- modrinth.com/mod/altcore
- Owner
- Altarmo
- Published
- 2025-04-22
- Updated on Modrinth
- 2026-07-03
- Facts verified
- 2026-10-15