Entity Custom Data

Name: Entity Custom Data
Author: NullSu

Entity Custom Data lets a datapack store and read custom NBT data on entities, with a control panel and automatic cleanup of dead entities.

FabricForgeNeoForgeQuiltServer required, client optionalBSD 2-Clause LicenseOpen source1.21 – 1.21.4

What it does

The mod turns on custom data entities through a datapack, and it supports two entities that accept custom data. A function opens a control panel that explains the available commands. Servers run the mod, while a client can also install it without needing it to join.

Dead entities that carry custom data are deleted automatically, and players are excluded from that cleanup. Deletion can be controlled, so server owners decide when entities are removed. Removing data requires the DELETE special option, which is saved and used through a single command. The mod is published for Fabric, Forge, NeoForge and Quilt for 1.21 – 1.21.4, released under the BSD 2-Clause License as open source.

Key features

Custom data entities
A datapack can enable custom data on entities, with support for two entity types that accept it.
Control panel
A function opens a help panel that lists the controls for working with entity custom data.
Automatic cleanup
Dead entities holding custom data are removed automatically, while players are left untouched.
Controlled deletion
Deletion can be checked before it runs, and the DELETE special option is required to remove data.

Gallery

In-game · The functions using in the game

Compatibility

Latest build for each game version and loader.

Version

1.21.4Release3.0+modRelease3.0+modRelease3.0+modRelease3.0+mod

1.21.3Release3.0+modRelease3.0+modRelease3.0+modRelease3.0+mod

1.21.2Release3.0+modRelease3.0+modRelease3.0+modRelease3.0+mod

1.21.1Release3.0+modRelease3.0+modRelease3.0+modRelease3.0+mod

1.21Release3.0+modRelease3.0+modRelease3.0+modRelease3.0+mod

ReleaseBetaAlphaNot available

Only full game releases are shown. This mod publishes no snapshot builds.

Use cases

Datapack entity tracking

A map or server datapack can attach custom data to mobs and keep it tidy by clearing it when the entity dies.

Server-side clean-up

Server owners can prevent stale entity data from piling up without writing their own removal logic.

Who it’s for: Datapack authors and server owners who need custom data on entities and a way to remove it when those entities die.

How it compares

Full comparison

Deadly Entity Data is a Fabric and NeoForge mod for 1.21.1, open source under the MIT License, and it runs on client and server. Polyenergy is server-side only, open source under the GNU General Public License v3.0 or later, and published for Fabric and Quilt for 1.21 – 1.21.4, so players need nothing installed.

Mod	Loaders	Game versions	Environment	Updated
Entity Custom Data	Fabric, Forge, NeoForge and Quilt	1.21 – 1.21.4	Server required, client optional	2025-01-13
Deadly Entity Data	Fabric and NeoForge	1.21.1	Client and server	2025-11-03
Polyenergy	Fabric and Quilt	1.21 – 1.21.4	Server-side only	2025-03-13

Questions

Does Entity Custom Data need to be installed on the server?

Yes. The server requires the mod, while the client may run it as an optional addition.

Which loaders does Entity Custom Data support?

Files are published for Fabric, Forge, NeoForge and Quilt, with the latest release built for 1.21.4.

Can players be deleted by the automatic cleanup?

No. Dead entities are removed, but players are excluded from the automatic deletion.

In the catalog

Entity Custom Data is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 17,979 mods support Minecraft 1.21.4.