Astruct
by SkyeShade
Astruct is a NeoForge optimization mod that plans and places large jigsaw-based structures without stalling the server, with the planning running off the main thread.
What it does
Astruct generates jigsaw structures far beyond vanilla limits. Its planning runs off-thread, so heavy jigsaw expansion stays outside the main server thread and avoids TPS spikes. Finished plans go into a placement queue keyed to the chunks each piece needs, and blocks are written only once the required chunks are loaded. Structures can also be shipped as JSON content.
The world is divided into partitioned cells with spacing rules. Each cell receives a deterministic, seed-based center for every structure ID, so placement stays consistent across runs. A proximity scan lets Astruct pre-plan cells well ahead of players who roam the map, and a periodic chunk-load sweep places only the pieces whose chunks are already loaded. Astruct also plugs into vanilla structure locate, so commands that search for structures keep working.
Astruct is released under the MIT License, is open source, and is published for NeoForge on 1.21.1 only, with the latest file 0.1.1 dated 2026-01-11. It is server-side only, so players join without installing it, and it requires the code of its own project to be present on the server. Source code is public.
Key features
Async structure generator
Jigsaw structures are planned and expanded off the main thread, so large layouts do not freeze the server.
Thousands of jigsaw pieces
Planning handles very large jigsaw layouts, including structures with thousands of pieces, without stalling the game loop.
Placement queue
Finished plans enter a queue keyed to chunks, and blocks are written only after the required chunks have loaded.
Proximity scan
Cells near roaming players are pre-planned ahead of time, so structures appear without waiting on generation.
Deterministic cell placement
A seed-based center is assigned to each structure ID inside its cell, keeping positions repeatable.
JSON content
Structures can be added as JSON definitions, letting data packs define new jigsaw content.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
Structure Configurator is server-side only, open source under the MIT License and published for NeoForge 1.21.1, so it covers the same version with a different focus on configuration. CleanJoin is server-side only, not open source, released under All rights reserved, and covers NeoForge 1.21.1 – 1.21.11. More Structure Control is client and server, open source under the MIT License, and spans Forge and NeoForge across 1.20.1 – 1.21.1, so both sides must run it.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Astruct | NeoForge | 1.21.1 | Server-side only | 2026-01-11 |
| Structure Configurator | NeoForge | 1.21.1 | Server-side only | 2026-06-03 |
| CleanJoin | NeoForge | 1.21.1 – 1.21.11 | Server-side only | 2026-07-22 |
| More Structure Control | Forge and NeoForge | 1.20.1 – 1.21.1 | Client and server | 2026-05-28 |
Questions
Does Astruct need to be installed on the client?
Which loader and version does Astruct support?
Can Astruct structures be defined without Java code?
In the catalog
Astruct is one of 3,545 Optimization mods on ModsFinder, and one of 1,250 Optimization mods for NeoForge. 32,366 mods support Minecraft 1.21.1.
More from SkyeShade
Similar mods
What the author says
Astruct lets you generate massive jigsaw-based structures without freezing the server. It plans structures off-thread, queues placements, and only builds blocks once the required chunks are loaded.
Official listing
- Modrinth page
- modrinth.com/mod/astruct
- Owner
- SkyeShade
- Published
- 2025-10-11
- Updated on Modrinth
- 2026-01-11
- Facts verified
- 2026-10-15