Liquid Lab
Liquid Lab is a Fabric library that gives developers a fluid API for creating custom fluids and gases in Minecraft Java Edition 1.21.1.
What it does
The library gives developers a way to create custom fluids and gases. Developers register fluid types, attach mixing rules and define how entities behave inside them, all from one API. Fabric API is required, and the mod runs on client and server, so both the server and every player need it. Latest file 2.2.0 for 1.21.1 was published on 2026-10-14, the first release was on 2026-04-09, and the code is open source under the MIT License.
Fluid mixing is defined with JSON files placed in a fluid mixing folder under the mod namespace. Each file names the fluid tags involved, so the mixing rules stay separate from Java code. Interactions are handled by methods that react when an entity first touches a fluid or stands within one, which gives developers a place to add splashing and other reactions without writing collision logic from scratch.
Key features
Custom fluids and gases
A single API covers the registration of fluid types, including gases, for mods that add new liquids to a world.
Entity entry and collision hooks
Callbacks fire when an entity first touches a fluid and while it is within one, with the block position passed along.
Fluid mixing from JSON
Mixing outcomes are written as JSON files in a fluid mixing folder, referencing fluid tags in the mod namespace.
Splash and drip particles
Helper methods register splash, dripping, falling and landing particles for each fluid, separately from the fluid itself.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Who it’s for: Mod developers building new fluids or gases for Fabric on Minecraft 1.21.1. Players use the library only indirectly, through the mods built on it.
How it compares
Flyd is a Fabric fluid mod for 1.21.1 under the MIT License and open source, with the same client and server environment. Fluid Levels is client-side only and open source under the MIT License, covering 1.20.1 – 1.21.11, so it works where Liquid Lab does not run on the server. Reservoir Fluid API is open source under the GNU Lesser General Public License v2.1 or later and built for 1.20.1 only.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Liquid Lab | Fabric | 1.21.1 | Client and server | 2026-10-14 |
| Flyd | Fabric | 1.21.1 | Client and server | 2025-03-29 |
| Fluid Levels | Fabric | 1.20.1 – 1.21.11 | Client-side only | 2026-02-15 |
| Reservoir Fluid API | Fabric | 1.20.1 | Client and server | 2026-09-23 |
Questions
Does Liquid Lab need Fabric API?
Does the server need Liquid Lab?
Can Liquid Lab add gases as well as liquids?
Where is the source code for Liquid Lab?
In the catalog
Liquid Lab is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 32,366 mods support Minecraft 1.21.1.
Similar mods
What the author says
To add a fluid mix, first create a folder named fluid_mixing in the namespace folder. Files here should be JSON files named as a valid fluid tag for that namespace to fuction properly. Contains methods related to fluid interactions, such as splashEntity for use in onEntityEntry to make custom splashing effects with…
Official listing
- Modrinth page
- modrinth.com/mod/liquid-lab
- Owner
- HersheyLightning
- Published
- 2026-04-09
- Updated on Modrinth
- 2026-10-14
- Facts verified
- 2026-10-15