This mod allows you to see a preview window of a shulker box contents when hovering above it in an inventory by pressing shift.

Supports both Fabric and Forge

On Fabric:

Fabric Loader and Fabric API are required 

Mod Menu is recommended (but not required) for in-game configuration

On Forge:

Cloth Config API is required

Features:

Compact Preview

Press shift (by default) while hovering an item.

Full Preview

Press alt+shift (by default) while hovering an item to shows its full contents where each contained stack is displayed in the correct slot.

Other Containers

The preview also works with items obtained in creative mode using control + pick block such as chests, furnaces, barrels, etc...
Works with most modded containers as well.

Loot Tables

The name of the loot table is displayed in the tooltip if the hovered item as one.
This option is disabled by default.

Configurability

Most aspects of the mod can be configured through the config menu. To access it, in the mod menu select ShulkerBoxTooltip an then click on the gear icon.
See the in game documentation or the wiki for info about each option. The config file can be found at <minecraft folder>/config/shulkerboxtooltip.json

Colors!

The color of the preview window changes depending on the color of the shulker box, you can disable it in config.

Server support

The mod can also be installed server-side (optional) to provide extra features such as ender chest preview.

Supported Versions

The mod has releases for Minecraft 1.14 to 1.19.1 (Fabric) and Minecraft 1.18.2 to 1.19.1 (Forge)