Anatomy of an Instance Folder

Where the instance folder lives

Each GDLauncher instance sits in a subfolder of the runtime path:

<runtime_path>/
└── instances/
    └── <shortpath>/        ← the instance folder

<shortpath> is a sanitized version of the instance’s display name. Right-click the instance in GDLauncher and pick Open Folder to jump there.

What’s inside

The instance folder splits into a few things GDLauncher tracks at the top level, plus an instance/ subfolder which is Minecraft’s actual game directory. Some folders are always present; many are created on demand the first time something writes to them.

<shortpath>/
├── instance.json          ← GDLauncher's metadata for this instance (always present)
├── packinfo.json          ← Modpack pairing info (only for paired modpacks)
├── icon.png | icon.webp   ← Custom icon (only if you set one)
├── logs/                  ← GDLauncher's per-instance launcher logs
└── instance/              ← Minecraft's game directory
    ├── mods/              ← Mod JARs
    ├── config/            ← Mod configs
    ├── shaderpacks/       ← Shader packs (if you've installed any)
    ├── options.txt        ← Minecraft client settings (after first launch)
    ├── logs/              ← Minecraft's session logs (latest.log etc.)
    ├── saves/             ← Worlds (created when you generate one)
    ├── screenshots/       ← F2 screenshots (created on first F2)
    ├── crash-reports/     ← Crash dumps (only if the game has crashed)
    ├── resourcepacks/     ← Custom resource packs (when you add one)
    ├── datapacks/         ← Global data packs (per-world packs live under saves/<world>/datapacks)
    └── (pack-specific)    ← kubejs/, defaultconfigs/, packmenu/, etc. only if the modpack ships them

Don’t be surprised if some of these are missing from a fresh instance. The launcher and Minecraft only create what they need, when they need it. An instance you’ve never played has no saves/, no screenshots/, no options.txt. A vanilla instance has no mods/ or config/.

What each thing holds

Top-level files

• instance.json: GDLauncher’s metadata, name, icon path, modloader and version, Minecraft version, when you created it, when you last played, total play time. Always present.
• packinfo.json: A hash manifest of which files came from the modpack. Lets the launcher tell apart pack-managed mods from anything you added yourself. Only present for instances paired with a CurseForge or Modrinth modpack.
• icon.png or icon.webp: The custom icon you uploaded. Missing if you’re using the default.

logs/ (top-level)

GDLauncher’s own per-instance logs. These are what the View Logs action in the right-click menu shows you. They cover the launcher’s view of the launch (Java arguments, asset downloads, mod loader install, exit code) and are useful when the game never gets far enough to write its own log.

instance/mods/

The mod JAR files. Minecraft loads everything in here at startup, subject to the mod loader’s rules. The launcher tracks which mods belong to an instance in its database (keyed by filename and content hash), there are no sidecar files. JARs you drop in by hand are picked up too; the launcher just won’t have CurseForge/Modrinth metadata for them.

instance/config/

One subfolder or file per mod. This is where mod settings persist. Most mods write config/<modid>.toml or a config/<modid>/ directory. Editing these by hand is usually safe; many mods read changes on game restart.

instance/resourcepacks/, instance/shaderpacks/, instance/datapacks/

Asset packs. Resource packs change textures and sounds, shader packs change rendering (require Iris/OptiFine/etc. installed as a mod), data packs add recipes/loot/functions. Data packs intended for a specific world live under saves/<world>/datapacks/ instead. These folders are only created when you actually have content for them.

instance/saves/

Each world is one subfolder. Inside, level.dat is the world’s master file, region/ has the chunk data, playerdata/ has per-player state, datapacks/ has world-scoped data packs. To back up a world, copy the whole <world>/ folder. The saves/ folder itself appears the first time you generate a world.

instance/screenshots/

Anything you’ve pressed F2 in. PNGs, named by timestamp. Created the first time you take a screenshot.

instance/logs/ and instance/crash-reports/

Minecraft’s own diagnostic output. logs/latest.log is always the most recent launch (rolled into a logs/<date>-1.log.gz on the next launch). crash-reports/ holds full crash dumps when the game dies hard, and only appears once there’s actually been a crash.

instance/options.txt

Minecraft’s client settings (graphics, controls, sounds). Plain text, key=value. Editable if you really want to.

Modpack-specific folders

Many large modpacks ship extra folders. The most common:

• kubejs/: KubeJS scripts (server_scripts/, client_scripts/, startup_scripts/, data/, assets/). Pack authors use this for runtime tweaks.
• defaultconfigs/: A snapshot of “what the configs should look like by default”. The pack’s launch script copies missing entries into config/ on each start.
• packmenu/: Pack-themed main-menu assets (custom buttons, backgrounds, splash text).
• defaultsettings/: Similar to defaultconfigs/, but for options.txt and keybindings.

These only exist if the pack ships them. Vanilla and most custom instances don’t have any.

What’s safe to delete

A note on locked modpack instances

The instance folder is just a folder on disk; the lock that GDLauncher applies to modpack instances is enforced in the UI, not the filesystem. Dropping a JAR into instance/mods/ of a locked instance works mechanically, the launcher just won’t be aware of it through the Addons tab. Removing such a file requires going back to the filesystem. For safer workflows, open the instance, go to the Settings tab, and click Unlock in the Modpack section first.