Where apps hide your files

Kerbal Space Program: GameData, saves and ships

Updated 2026-10-28 · 5 min read

Unlike most Mac games, Kerbal Space Program keeps your saves and mods inside the game's own folder rather than a separate data folder. That makes them easy to lose on a reinstall, so here is where they are and what to copy first.

The location

Kerbal Space Program keeps your saves, ship designs and mods inside the game's own folder, not in Library's usual save places. For a Steam install on a Mac, that folder is:

~/Library/Application Support/Steam/steamapps/common/Kerbal Space Program

The KSP wiki gives this as the Mac default, and Steam's cloud settings for the game sync files from the saves, Ships and Missions folders of the install. The quickest route is from Steam: right-click the game in your library and choose Manage > Browse local files. That opens the right folder even if you moved your Steam library to another drive.

Because the default path is inside ~/Library, Finder hides it. Choose Go > Go to Folder (⇧⌘G), paste the path and press Return, or use:

open ~/Library/Application\ Support/Steam/steamapps/common/Kerbal\ Space\ Program

A copy bought outside Steam (from the KSP store or GOG) uses the same layout in whatever folder you installed it; the CKAN mod manager looks for standalone copies in /Applications/Kerbal Space Program.

What you will find there

Item	What it is
KSP.app	The game itself
GameData	Where mods go. Each mod is a folder in here, next to the stock Squad folder
saves	One folder per save game, named after the save
Ships	The stock craft, in VAB and SPH sub-folders
KSP.log	The game's own log (see below)

GameData sits beside KSP.app, not inside it: CKAN identifies a KSP install by finding a GameData folder in the same folder as the game. You do not need Show Package Contents to install mods.

Inside a save

Each folder under saves is one game. The file that matters is persistent.sfs, which the game writes as it autosaves and when you leave the save; quicksave.sfs appears once you quicksave. Each save also has its own Ships/VAB and Ships/SPH folders holding the craft you built in that save, as .craft files.

So your ship designs are inside each save, while the top-level Ships folder holds the stock craft. The KSP wiki warns against removing that top-level folder, because the editors and save menus need it. Copying a .craft file into another save's VAB or SPH folder makes the design available there.

Installing mods

Most mods ship as a folder to drop into GameData. Quit the game, unzip the download, and read the mod's instructions first, because some mods need others installed alongside. Keep the folder layout the mod's instructions show. A common slip when unzipping is ending up with GameData/GameData/..., which breaks mods that expect their own path. CKAN, the community mod manager, can install and update mods for you and handles dependencies.

To remove a mod, quit the game and move its folder out of GameData to your Desktop, so you can put it back. Saves that use the mod's parts may not load without it. Leave GameData/Squad (and SquadExpansion, if you own the expansions) alone: they are the game's own content.

The trap: reinstalling

Because saves and mods live in the install folder, anything that removes or rebuilds that folder can take them with it. Before you uninstall, move the game or reinstall:

1. Quit the game.
2. Copy saves and GameData (and any craft you added to the top-level Ships folder) to a folder outside the game, such as your Desktop.
3. Reinstall, start the game once, and quit.
4. Copy saves back, then add mods from your copy of GameData one at a time, skipping Squad and SquadExpansion.

KSP on Steam keeps .sfs saves and .craft files in Steam Cloud. That is why a craft or save you deleted can come back: Steam restores it from the cloud. Turn off Keep game's saves in the Steam Cloud in the game's Steam Properties while you tidy up or restore old files.

Logs

Mod authors usually ask for KSP.log, which the game writes in its own folder next to KSP.app. KSP is also a Unity game, and Unity writes a Player.log under ~/Library/Logs; the exact sub-folder depends on the Unity version, so list it:

ls ~/Library/Logs | grep -i -e unity -e squad

Moving to a new Mac

Copy saves, your own craft and your mods, not the whole install, which is large and re-downloads from Steam anyway. On the new Mac, install the game, start it once, quit, and copy the folders in. Mods must match the game version, so update them if the new install is a newer build. PCGamingWiki notes that saves from the Windows version also work on a Mac.

Why searching misses these

Spotlight and Finder searches leave out ~/Library, and the Steam install folder sits in that hidden area. A save is a folder named whatever you called it, with a plain persistent.sfs inside.

Finding a save or a mod again

Type persistent.sfs into Everywhere and you get one row for every save game, each with its folder, which is the quick way to see which save is which and when it last changed. Typing .craft lists every ship design across your saves, and a mod's name finds its folder in GameData. The Steam folder is in ~/Library/Application Support, which is scanned without extra permission; it searches names only, not what is inside a file.

Common questions

Where is the GameData folder on a Mac?

In the game folder, beside KSP.app: for Steam, ~/Library/Application Support/Steam/steamapps/common/Kerbal Space Program/GameData. In Steam, right-click the game and choose Manage > Browse local files to open it.

Where are Kerbal Space Program saves on a Mac?

In the saves folder in the game's install folder, with one folder per save and a persistent.sfs file inside. Each save's own craft are in its Ships/VAB and Ships/SPH folders.

Will I lose my saves if I reinstall KSP?

They can be lost, because they sit inside the install folder. Copy saves and GameData elsewhere before you uninstall or move the game.

Why does a deleted KSP craft keep coming back?

KSP on Steam syncs .sfs and .craft files with Steam Cloud, which can restore them. Turn off Keep game's saves in the Steam Cloud in the game's Steam Properties while you tidy up.