Runtime Registry Extender
by Nerjal_Nosk
Runtime Registry Extender is a Fabric library that lets mod authors add entries to Minecraft registries while the game is already running.
What it does
The library lets a mod register new entries during play rather than only at startup. Authors set up the extension with a dedicated entrypoint, and the registration code has to run before registries are initialised. Only new entries can be added: frozen base registries are not modified, which keeps the game stable. It also allows registry keys to be provided so that some registries become extendable, and it lets block state adapters receive invalid block states and replace them. Adapters only receive raw data in NBT format, and so far only block states and block entity data are affected.
The library is intended for servers and worlds that supply extra values to players, who can take them into account without restarting the game or launching a separate configuration. Its scope is deliberately narrow, because registries change only at a few points in the game loop. Related assets such as models, textures and translations must still be present locally or be provided by a server resource pack. Fabric is the only loader, and files target 26.1 – 26.2 under a custom license that is not open source. Installation needs Fabric API, and the mod runs on the client and on the server.
Key features
Runtime registry entries
Mods can add new entries to supported registries while the game runs, without a restart.
Extendable registry keys
Authors provide registry keys so that other registries become extendable.
Block state adapters
Adapters can replace invalid block states, and they receive raw NBT data read from the region.
Provided extra values
Servers and worlds can supply values that players take into account, while frozen base registries stay untouched.
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: Mod authors who need to add registry entries at runtime, and server owners who want to supply extra content for their worlds without restarting.
How it compares
Dynamic Registries Modifier is open source under the CC0 1.0 Universal license, runs on Fabric for 1.21.1 – 1.21.8 and can be used on the client or the server. Registry Helper Lib is open source under the GNU General Public License v3.0 or later, covers 1.20 – 1.21.11 and is optional on either side. SolLiLib is not open source, is released under All rights reserved and, like this mod, must be installed on both client and server, but it targets 26.1.2 – 26.2.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Runtime Registry Extender | Fabric | 26.1 – 26.2 | Client and server | 2026-08-07 |
| Dynamic Registries Modifier | Fabric | 1.21.1 – 1.21.8 | Client or server, optional | 2025-08-23 |
| Registry Helper Lib | Fabric | 1.20 – 1.21.11 | Client or server, optional | 2026-02-25 |
| SolLiLib | Fabric | 26.1.2 – 26.2 | Client and server | 2026-08-24 |
Questions
Does Runtime Registry Extender need Fabric API?
Does the server need the mod for players to join?
Can Runtime Registry Extender change frozen base registries?
In the catalog
Runtime Registry Extender is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 13,894 mods support Minecraft 26.2.
More from Nerjal_Nosk
Similar mods
What the author says
An absurdly twisted library mod to add entries at runtime to the just as absurdly twisted Minecraft registries. Please note that "runtime" here is limited to a few phases of the game loop to avoid random breakage.
Official listing
- Modrinth page
- modrinth.com/mod/rre
- Owner
- Nerjal_Nosk
- Published
- 2026-07-10
- Updated on Modrinth
- 2026-08-07
- Facts verified
- 2026-10-15