RemapIDs
RemapIDs is a data-driven registry remap and alias system for modpack developers. Define JSON mappings that redirect item, block, entity, fluid, tag, recipe, and loot table IDs to alternative IDs at runtime — enabling seamless world migration when mods are removed, replaced, or reorganized.
Key Features
| Feature | Description |
|---|---|
| Vanilla & Modded Remapping | Remap vanilla IDs to modded IDs (and vice versa) — including live block replacement with block state remapping |
| Wildcard Expansion | Use * patterns to remap entire families of IDs in a single entry |
| Type Filtering | Optionally limit which remap types (block, item, recipe, etc.) a mapping applies to |
| Chain Flattening | Automatically resolves multi-step chains (A→B, B→C becomes A→C) |
| Circular Detection | Rejects circular mappings with clear error logging |
| Tag Remapping | Redirect tag references with the # prefix, including tag-to-item conversion |
| Numerical ID Support | Use pre-1.13 numerical block/item IDs as sources for legacy world migration |
| Identify Command | Look up registry IDs of blocks and items in-game with /remapids id |
| Multi-File Configs | Organize remaps across multiple JSON files, processed alphabetically |
Supported Platforms
| Loader | Minecraft Version | Status |
|---|---|---|
| Forge | 1.20.1 | Supported |
| Fabric | 1.20.1 | Supported |
| Fabric | 1.21.1 | Supported |
| NeoForge | 1.21.1 | Supported |
How It Works
RemapIDs operates through two categories of remaps:
- Registry remaps (block, item, fluid, entity_type) are injected into the game registries after all mods have registered their content. These require a full game restart to apply. For block remaps, block state IDs are also remapped so network serialization stays consistent.
- Reloadable remaps (tag, recipe, loot_table) are applied when datapacks load and can be refreshed with
/reload.
RemapIDs is configured through JSON files placed in config/remapids/remaps/. The /remapids id command is available in-game to help identify block and item registry IDs — see the Commands Guide.