DeltaChunk

Chunks are saved in their original .mca region format, but DeltaChunk keeps only the data that cannot be regenerated from the world seed, such as blocks placed or broken by a player and the contents of block entities. Terrain that the seed can recreate is left out of the save, which is how the mod reduces the size of region files. Because the format stays .mca, existing tools that read those files still apply.

The mod is built to run alongside other optimization mods such as Aether and AOA3, but it is not compatible with Twilight Forest. Commands add or remove the data that gets saved, and enchantments follow similar commands. The server operator should back up the world before installing DeltaChunk and keep the old world saved, because the mod does not know which blocks were placed before it was added. A player generator should also be set up before blocks are placed or broken.

Installation needs NeoForge on both the client and the server. The files cover 1.21.1 – 26.3 across ten release versions, the latest being 0.2.1-1.21.7 for 1.21.7, released on 2026-10-08. The code is open source under the MIT License, and the project is not recommended for multiplayer servers because of potential bugs and higher CPU use when region size is exchanged.