Kleene Builds
by csclub05
Kleene Builds gives builders a way to apply large-scale design changes to a selected area without leaving the game, on Fabric.
What it does
To mark the region, a builder picks two opposite corners, and the blocks at both corners fall inside the selected area. The mod then lets the builder pick an operation, such as adding block dithering or spawnproofing glass, adjust its options, and execute it so the changes apply to the selected part of the build. The selection tool defaults to rotten flesh, and that item can be changed on the Settings page, while the View Operations page lists the available operations.
The mod is aimed at singleplayer worlds, where a builder works alone on a large project. Since an operation can alter a large number of blocks in one pass, it is wise to save copies of valuable worlds before applying big changes. Client and server both need the mod, so the server and every player must run it, and the code is released under the MIT License without being open source.
Installation requires only Fabric as the loader. Files are published for 1.20.1, 1.21.4, 1.21.5 and 1.21.6, under the 1.20.1 – 1.21.6 range with 1.21.6 as the latest, and the first build went out on 2026-08-24.
Key features
Two-corner area selection
A region is defined by choosing two corners, and both corner blocks belong to the selection.
Block dithering and glass spawnproofing
Operations such as adding block dithering or spawnproofing glass can be applied to the chosen area.
Adjustable operation options
Each operation has options that can be changed before it is executed on the selection.
Operation and settings pages
A View Operations page lists the operations, and a Settings page controls the selection tool's item.
Gallery
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: Builders working in Fabric singleplayer worlds who need to apply broad, repeated changes to a selected part of a build.
How it compares
MathChat is a Fabric mod for 1.21.4 that runs on the server only, and it is released under the Apache License 2.0 without being open source. BlockMixer is a Fabric client-side mod for 1.20 – 1.21.5 under the MIT License, and it is open source. Hollower runs on client and server for 1.21.11 under a Creative Commons Attribution Non Commercial 4.0 license.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Kleene Builds | Fabric | 1.20.1 – 1.21.6 | Client and server | 2026-10-12 |
| MathChat | Fabric | 1.21.4 | Server-side only | 2025-11-06 |
| BlockMixer | Fabric | 1.20 – 1.21.5 | Client-side only | 2025-05-22 |
| Hollower | Fabric | 1.21.11 | Client and server | 2026-03-18 |
Questions
Does Kleene Builds need to be installed on the server?
Which loader does Kleene Builds use?
Which game versions does Kleene Builds support?
Should Kleene Builds be used on a multiplayer server?
In the catalog
Kleene Builds is one of 36,990 Utility mods on ModsFinder, and one of 25,772 Utility mods for Fabric. 13,625 mods support Minecraft 1.21.6.
More from csclub05
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What the author says
Kleene Builds is a Minecraft Java Fabric mod that helps builders make large-scale design changes without leaving the game. You select the part of your build you want to work on and let Kleene Builds apply a controlled building operation to that area.
Official listing
- Modrinth page
- modrinth.com/mod/kleene-builds
- Owner
- csclub05
- Published
- 2026-08-24
- Updated on Modrinth
- 2026-10-12
- Facts verified
- 2026-10-15