Dynamic Patcher
by qendolin
Dynamic Patcher lets Fabric mod developers drop Mixin source files into a folder and have them compiled and applied at runtime, with no separate build step.
What it does
Mixin patches are written as Java source and placed in a directory the mod reads when the game starts. The sources are turned into classes during startup by the Eclipse Compiler for Java (ECJ), then loaded as Mixins. A file that lacks a package declaration is placed in the default package, and the mod remaps it to dynpatcher.generated before loading.
Compiled output is kept in an internal cache directory that holds bytecode files and an index. On later launches, cached class files are checked against the index using timestamps and SHA-256 content hashes, so unchanged sources are not compiled again. The mod has a configuration file for its settings, and the cache index is meant for the mod, not for manual editing.
The mod is for modders and pack makers testing Mixin changes without rebuilding a jar. It is a Fabric mod for 26.1 – 26.3, and either side can run it while neither needs it. Dynamic Patcher is open source under the CC0 1.0 Universal license, and its source code and issue tracker are public.
Key features
Runtime Mixin compilation
Mixin source files are compiled when the game starts and loaded without a separate build step.
Source folder with subdirectories
Patch sources go into one folder, and subdirectories can group them into a layout of the author's choosing.
Compiler cache
Compiled bytecode is stored and reused, so sources that have not changed are not recompiled on the next launch.
Default package handling
Sources without a package declaration are placed in the default package and remapped to dynpatcher.generated.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Testing Mixin changes
A developer can edit a Mixin source file and restart the game to see the change, without rebuilding a jar each time.
Pack-level patches
Pack makers can add Mixin sources to a folder to adjust behavior in a modpack, without shipping a compiled mod.
Who it’s for: Mod developers and pack makers who write Mixin patches in Java and want them compiled at runtime. Players who only install finished mods have no reason to use it.
Questions
Does Dynamic Patcher need to be installed on both sides?
Which game versions does Dynamic Patcher support?
Where are Mixin source files placed?
In the catalog
Dynamic Patcher is one of 36,990 Utility mods on ModsFinder, and one of 25,772 Utility mods for Fabric. 8,071 mods support Minecraft 26.3.
More from qendolin
Similar mods
What the author says
Dynamically compile and load Mixin patches from source at runtime. Paths are relative to the config/dynpatcher/patches/ directory.
Official listing
- Modrinth page
- modrinth.com/mod/dyn-patcher
- Owner
- qendolin
- Published
- 2026-07-23
- Updated on Modrinth
- 2026-07-23
- Facts verified
- 2026-10-15