Import & Export
Import modpacks from CurseForge, Modrinth, MultiMC, or Trident format — and export your instances in any format.
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Supported Formats
Polymerium supports four modpack formats for both import and export:
| Format | Extension | Notes |
|---|---|---|
| Trident (native) | .zip | Preserves the most metadata: tags, rules, overrides, icons, README, changelog |
| CurseForge | .zip | Industry standard; compatible with CurseForge app, Prism, etc. |
| Modrinth | .mrpack | Modern format; compatible with Modrinth app, Prism, etc. |
| MultiMC | .zip | Compatible with MultiMC, Prism Launcher, and derivatives |
Importing a Modpack
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Click the + button to create a new instance.
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Choose Import from file.
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Select the modpack archive.
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Polymerium auto-detects the format and imports:
- The metadata is parsed and written to your instance's
profile.json. - Pack files (configs, resources) are extracted to
import/. - Mods listed in the pack are resolved and downloaded to the shared cache.
- The metadata is parsed and written to your instance's
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Deploy and play.
Updating a modpack? If the instance was created from an import, you can re-import a newer version of the same pack. Polymerium replaces
import/with the new files while leavingpersist/untouched — files you've moved there are preserved.
Exporting an Instance
- Select an instance.
- Open the instance menu → Export.
- Choose the format, fill in metadata (name, author, version, summary).
- Polymerium packages the instance metadata +
import/files into the chosen format.
What Gets Exported
| Content | Included? |
|---|---|
| Mod list + versions | ✅ |
Config files (import/) | ✅ |
| Instance icon | ✅ |
| Modpack metadata (name, author, version) | ✅ |
| Saves, screenshots, personal configs | ❌ — if you've moved these to persist/, they stay in persist/ and aren't included in the export |
Format-Specific Notes
- Trident format preserves the most information: tags, deployment rules, account bindings, and extra files. Best for Polymerium-to-Polymerium sharing.
- CurseForge / Modrinth formats are widely compatible but lose Polymerium-specific features like tags and rules.
- MultiMC format is the most basic — just the mod list and configs.
Online vs. Offline Formats
Not all modpack formats work the same way under the hood:
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CurseForge and Modrinth formats are online — they contain references (package URLs) to mods hosted on those platforms, not the actual mod files. When you import one, the launcher resolves those references and downloads the mods.
This means a CurseForge modpack should ideally only reference CurseForge mods, and a Modrinth modpack should only reference Modrinth mods. If you mix sources, the modpack won't pass platform review when publishing.
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Trident and MultiMC formats are offline — they bundle the actual mod files inside the archive. No internet resolution needed on import.
Keep this in mind when choosing a format for publishing your modpack.
Migrating From Another Launcher
If you're coming from another launcher, check the migration guide: