Minecraft Registry

Registries

This content applies only to Java Edition.

Registries are a widely used game mechanism organizing values of the same type.

Categories

• Built-in registries: hardcoded; contents cannot be modified; shared across worlds.
• Writable registries: loaded from datapacks; world-bound and data-dependent.
• Network-synchronized registries: writable registries synced to clients via the registry_data packet during configuration.

Indexing

• Namespace IDs map to values (e.g. grass_block in the BLOCK registry).
• Numeric IDs are used only on the network to shorten data.
• Tags map to multiple values (e.g. #air = air + cave_air + void_air); tags are never hardcoded and can be defined by datapacks for any registry. Synced registries (all built-in + network-synchronized writable ones) sync tags via the update_tags packet.

Structure

Every writable registry has a deserializer (e.g. ENCHANTMENT ↔ enchantment format) and a datapack path P: files data/<N>/<P>/<I>.json register value N:I. Example: data/minecraft/jukebox_song/5.json registers minecraft:5. Tags: files data/<N>/tags/<P>/<I>.json (including subdirectories) create tag #N:I, e.g. data/minecraft/tags/block/mineable/axe.json → #minecraft:mineable/axe.

Registries themselves are registered in a special registry; they cannot be added or removed.