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.

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Polymerium
Overview
Fabulously Optimized
SetupDetails →
43packages
Fabric1.21.5
Play Time
8.3h
Snapshots
3
Everything is ready
LAUNCH
ST
Stewie
Win / Linux / macOS
MIT License
Fabric · Forge · NeoForge · Quilt

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.

profile.json
{
  "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).

trident — MCP server
$ trident instance create my-pack --version 1.21.4
$ trident package add modrinth:sodium
$ trident package add modrinth:iris
$ trident instance build my-pack
$ trident instance run my-pack
✓ Instance "my-pack" deployed and launched.
$ trident --mcp
MCP server listening on stdio... (30+ tools registered)
Exclusive

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.

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Up and Running in 3 Steps

github.com/d3ara1n/Polymerium/releases
Polymerium-1.0.0-win-x64.exe
67.8 / 89.2 MB
01

Download

Download the installer for your platform from GitHub Releases.

New Instance
Version
1.21.5
Loader
Fabric
Forge
Quilt
Create
02

Create Instance

Pick a Minecraft version, choose a loader, add the mods you want.

Fabulously Optimized
Deploying instance…
Launching…
ST
Stewie
03

Play

One-click deploy and launch. That's it.

Frequently Asked Questions

Ready to Save Disk Space?

Download Polymerium and experience metadata-driven instance management.

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