---
title: Polymerium vs Prism Launcher
description: A detailed feature comparison between Polymerium and Prism Launcher, two popular Minecraft launchers.
---

## Overview

Polymerium and Prism Launcher are both open-source Minecraft launchers that support multiple instances, mod loaders, and modpack platforms. However, they take fundamentally different approaches to instance management and storage.

### Key Difference at a Glance

| Aspect | Polymerium | Prism Launcher |
|--------|:----------:|:--------------:|
| **Instance representation** | Metadata file (`profile.json`) + shared cache | Full file copy (isolated `.minecraft` folders) |
| **Storage model** | Symlink-based deduplication | File duplication with optional hard/symbolic links |
| **Architecture** | Compile-on-read (metadata → deploy) | File-based instance folders |
| **License** | MIT | GPL-3.0 |

---

## Feature Comparison

### Storage & Disk Usage

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **Shared mod cache** | ✅ Central cache, symlinked into instances | ❌ Each instance stores its own copies |
| **Disk space savings** | 60–80% vs traditional launchers | No deduplication by default |
| **Symlink support** | ✅ Cross-platform (Win/Linux/macOS) | ✅ Supported (Unix only), with hard links and reflinks |
| **Modpack version switching** | Seconds (metadata change) | Import new copy (full duplication) |

**Real-world example:** 5 instances with identical modlists (50 mods, 2GB total)

- **Prism Launcher:** ~10GB disk usage (5 × 2GB)
- **Polymerium:** ~2GB disk usage (2GB shared cache + metadata)

---

### Instance Architecture

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **Instance definition** | Single `profile.json` file | `instance.cfg` + full folder structure |
| **File organization** | 4-layer model (import/live/persist/build) | Single `.minecraft` folder |
| **Reset/rebuild** | Clear `build/` and `live/`, redeploy from metadata | Manual file deletion/reimport |
| **Modpack updates** | In-place, `import/` replaced, `persist/` preserved | Import new copy (duplicates files) |

**Polymerium's 4-layer model:**

```
instances/my-pack/
├── import/    ← Modpack source (read-only)
├── live/      ← Working copy (in-game changes)
├── persist/   ← User-preserved files (survives updates)
└── build/     ← Final game directory (disposable)
```

This separation means:
- Modpack updates don't overwrite your custom settings (`persist/`)
- Resetting doesn't delete your world saves (`persist/saves/`)
- The game directory (`build/`) is rebuildable from metadata

---

### Mod Loader Support

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **Fabric** | ✅ | ✅ |
| **Forge** | ✅ | ✅ |
| **NeoForge** | ✅ | ✅ |
| **Quilt** | ✅ | ✅ |
| **LiteLoader** | ❌ | ✅ |
| **Ornithe / LegacyFabric / Rift** | ❌ | ✅ (as search filters) |
| **Custom loader versions** | ✅ Select specific versions | ✅ Via instance version editor (patch components) |
| **Instant loader switching** | ✅ Update metadata, redeploy | ⚠️ Create new instance or manual patch

**Polymerium advantage:** Switch from Forge to NeoForge in seconds — just update the `loader` field and redeploy. No re-downloading the same mods.

**Prism Launcher advantage:** Strong instance patching capabilities — customize core components and loader versions via the Version editor. Broader loader support including legacy loaders.

---

### Modpack Import/Export

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **CurseForge import** | ✅ | ✅ |
| **Modrinth import** | ✅ | ✅ |
| **MultiMC import** | ✅ | ✅ (MultiMC legacy support) |
| **Trident format** | ✅ Native format | ❌ |
| **CurseForge export** | ✅ | ✅ |
| **Modrinth export** | ✅ | ✅ |
| **MultiMC export** | ✅ | ✅ |
| **Modpack updates** | In-place, `import/` refresh | Import new copy (full duplication) |

---

### Account Management

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **Microsoft account** | ✅ (Device Code Flow OAuth) | ✅ |
| **Offline account** | ✅ | ✅ |
| **Authlib Injector** | ✅ (Third-party auth / Yggdrasil) | ❌ |
| **Trial account** | ✅ | ❌ |
| **Per-instance accounts** | ✅ Bind different accounts to different instances | ❌ Global account setting |

---

### Mod Management

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **CurseForge integration** | ✅ Built-in | ✅ Built-in |
| **Modrinth integration** | ✅ Built-in | ✅ Built-in |
| **Tag-based organization** | ✅ Flexible tags, multi-tag filtering | ❌ Traditional categories |
| **Deployment rules engine** | ✅ Skip/redirect/normalize files by condition | ❌ |
| **Batch operations** | ✅ Bulk update, tag-based exclusion | ✅ Basic bulk operations |

**Deployment rules example (Polymerium):**

```json
{
  "selector": "And(Repository=curseforge, Kind=datapack)",
  "action": "Destination → datapacks/"
}
```

This redirects all CurseForge datapacks to a custom folder — useful for different datapack path conventions across loaders.

---

### Advanced Features

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **Snapshots** | ✅ Save/restore/diff entire game states | ❌ |
| **CLI** | ✅ 30+ commands (`trident`) | ❌ |
| **MCP Mode** | ✅ AI Agent integration (30+ tools) | ❌ |
| **Crash diagnostics** | ✅ 3-stage error classification + AI analysis | ⚠️ Basic crash log |
| **Git-friendly modpack dev** | ✅ Instance = JSON + assets, version-control ready | ⚠️ Requires manual zip export |
| **Playtime tracking** | ✅ Charts, weekly activity, total hours | ✅ Basic timer |
| **Widgets** | ✅ Text notes, network connectivity | ❌ |
| **Java auto-download** | ✅ Automatic from Mojang | ✅ |
| **Theme system** | ✅ Light/dark, custom accent, border radius | ✅ Basic theming |

---

### Platform & Localization

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **Windows** | ✅ | ✅ |
| **macOS** | ✅ ARM64 (Apple Silicon) | ✅ ARM64 |
| **Linux** | ✅ | ✅ |
| **English** | ✅ | ✅ |
| **Chinese** | ✅ Full localization | ✅ Weblate community translation |
| **Other languages** | ⚠️ Add manually | ✅ Weblate (370+ contributors) |

**Prism Launcher advantage:** Mature, battle-tested launcher with strong community support. Weblate project with 370+ contributors provides extensive localization. Strong instance patching capabilities via the Version editor. Broader mod loader support including legacy loaders.

---

### Open Source & Licensing

| Feature | Polymerium | Prism Launcher |
|---------|:----------:|:--------------:|
| **License** | MIT | GPL-3.0 |
| **Source code** | [GitHub](https://github.com/d3ara1n/Polymerium) | [GitHub](https://github.com/PrismLauncher/PrismLauncher) |
| **Fork of** | Original project | MultiMC |

---

## When to Choose Each

### Choose Polymerium if you:

- ✅ Have limited disk space or manage many instances with overlapping modlists
- ✅ Frequently switch between mod loaders or modpack versions
- ✅ Develop or maintain modpacks (Git-friendly workflow)
- ✅ Want to experiment safely (snapshots)
- ✅ Need offline or third-party auth (Authlib Injector, Trial)
- ✅ Prefer Chinese localization
- ✅ Want AI Agent automation (MCP mode)
- ✅ Need precise control over file deployment (rules engine)

### Choose Prism Launcher if you:

- ✅ Prefer a traditional file-based instance model
- ✅ Need GPL-3.0 licensing for your project
- ✅ Are already familiar with MultiMC-style instance folders
- ✅ Want strong instance patching (custom component/JSON editing)
- ✅ Need legacy loader support (LiteLoader, Ornithe, etc.)
- ✅ Want a mature, battle-tested launcher with strong community support (370+ Weblate contributors)

---

## Unique Polymerium Features

### MCP Mode & AI Integration

Polymerium is the **only Minecraft launcher with built-in MCP support**. Run `trident --mcp` and AI agents can:

- Create instances: `instance_create(...)`
- Add mods: `package_add("modrinth:sodium")`
- Take snapshots: `snapshot_create(...)`
- Deploy and launch: `instance_build(...)`

30+ tools cover the entire workflow — no other launcher offers this capability.

### Snapshots & Diff

Save the entire game state before making changes, then restore or compare later. Great for:

- Testing mod updates
- Experimenting with configurations
- Debugging crashes
- Rolling back broken setups

### Git-Friendly Modpack Development

Your instance source is clean: `profile.json` + `import/` + icon + README + CHANGELOG. Add a `.gitignore` to exclude `build/`, `live/`, `persist/`, and you have a version-controlled modpack ready for collaboration.

---

## Feature Matrix (Full)

| Feature | Polymerium | Prism Launcher |
|--------|:----------:|:--------------:|
| **Storage** |||
| Symlink-based deduplication | ✅ | ⚠️ Unix-only |
| Hard link support | ✅ | ✅ |
| Shared mod cache | ✅ | ❌ |
| Disk space savings | 60–80% | None |
| **Architecture** |||
| Metadata-driven instances | ✅ | ❌ |
| 4-layer file model | ✅ | ❌ |
| Compile-on-read deployment | ✅ | ❌ |
| **Mod Loaders** |||
| Fabric | ✅ | ✅ |
| Forge | ✅ | ✅ |
| NeoForge | ✅ | ✅ |
| Quilt | ✅ | ✅ |
| LiteLoader | ❌ | ✅ |
| Legacy loaders (Ornithe, Rift, etc.) | ❌ | ✅ (as filters) |
| Custom loader versions | ✅ | ✅ (Version editor) |
| **Modpacks** |||
| CurseForge import/export | ✅ | ✅ |
| Modrinth import/export | ✅ | ✅ |
| MultiMC import/export | ✅ | ✅ |
| Trident format | ✅ | ❌ |
| In-place modpack updates | ✅ | ⚠️ Import new copy |
| **Accounts** |||
| Microsoft | ✅ | ✅ |
| Offline | ✅ | ✅ |
| Authlib Injector | ✅ | ❌ |
| Trial | ✅ | ❌ |
| Per-instance binding | ✅ | ❌ |
| **Mods** |||
| CurseForge + Modrinth | ✅ | ✅ |
| Tag-based organization | ✅ | ❌ |
| Deployment rules | ✅ | ❌ |
| Batch update with exclusion | ✅ | ⚠️ Basic |
| **Advanced** |||
| Snapshots | ✅ | ❌ |
| CLI (`trident`) | ✅ (30+ commands) | ❌ |
| MCP Mode (AI Agents) | ✅ | ❌ |
| Crash diagnostics + AI | ✅ | ⚠️ Basic |
| Git-friendly modpack dev | ✅ | ⚠️ Manual export |
| Playtime tracking (charts) | ✅ | ✅ (basic) |
| Widgets | ✅ | ❌ |
| **Platform** |||
| Windows (x64) | ✅ | ✅ |
| Linux (x64) | ✅ | ✅ |
| macOS (ARM64) | ✅ | ✅ |
| English | ✅ | ✅ |
| Chinese | ✅ (built-in) | ✅ (Weblate) |
| Other languages | ⚠️ (add manually) | ✅ (Weblate, 370+ contributors) |
| **Other** |||
| Java auto-download | ✅ | ✅ |
| Theme system | ✅ | ✅ |
| Open source | ✅ (MIT) | ✅ (GPL-3.0) |

---

## Summary

Polymerium and Prism Launcher both provide robust Minecraft instance management, but they target different use cases:

- **Polymerium** innovates on the instance model — metadata-driven, symlink-based deduplication, and unique features like snapshots, MCP mode, and Git-friendly modpack development. Ideal for power users, modpack developers, and those who want automation and efficiency.

- **Prism Launcher** offers a traditional, battle-tested file-based approach with MultiMC heritage. Strong instance patching, broader loader support, and a mature Weblate-powered localization ecosystem with 370+ contributors. Solid choice if you want a mature launcher with strong community support and GPL licensing.

Both are excellent choices — pick the one that matches your workflow.