The Minecraft Launcher That Stores Each Mod Exactly Once
Metadata-driven instance manager with zero-duplication storage, snapshots, and a built-in CLI with MCP mode for AI agents.
An Instance Is a Description, Not a Folder Copy
Polymerium describes your game setup with a lightweight profile.json — version, loader, mod list. Instances are built on demand from a shared cache using symlinks. No files are copied. That means zero duplication, instant modpack switching, and Git-friendly version control.
{
"version": "1.21.4",
"loader": { "type": "fabric", "version": "0.16.9" },
"modloader": true,
"packages": [
"modrinth:sodium",
"modrinth:iris",
"modrinth:fabric-api"
]
}Built for Efficiency
Zero Duplication
Each mod file stored once, symlinked everywhere. Save 60–80% disk space.
Instant Switching
Change modpacks in seconds, not minutes. No file copying needed.
Snapshots
Save, restore, and diff entire game states. Experiment safely.
Git-Friendly Modpacks
Instance = one JSON file. Version control your modpack development.
CLI + MCP Mode
30+ commands for automation. Let AI agents manage your instances.
Privacy First
No ads, no telemetry, no data collection. Open source (MIT).
The Only Minecraft Launcher with Built-in MCP
Start the trident MCP server and let AI agents create instances, add mods, build deployments, and manage snapshots — 30+ tools covering the full workflow.
Up and Running in 3 Steps
Download
Download the installer for your platform from GitHub Releases.
Create Instance
Pick a Minecraft version, choose a loader, add the mods you want.
Play
One-click deploy and launch. That's it.