Dead Cells has several legitimate Windows save roots depending on storefront, which makes timestamps and launcher context more useful than the filename alone. Steam users should preserve app ID 588650 remote data; other editions may write under the install directory or LocalAppData. The save set also includes customGameData JSON separate from user_*.dat. SaveEditor recommends backing up both categories so a restored profile does not silently lose custom-mode configuration.
Known Dead Cells save-file structure
The researched filename or folder pattern is user_*.dat and customGameData_*.json. File-extension context: .dat, .json The documented format notes are: Dead Cells stores player data and custom-game configuration separately. Steam uses app-ID remote storage, while other desktop releases can use the installation save directory and Microsoft Store uses package-local/WGS-style storage.
Why an extension is not enough
A save filename can identify a likely container, but it does not prove the internal schema, game version, checksum rules, encryption state, or editability. A user_*.dat file can restore player progress without restoring custom-game JSON, so a partial copy may look inconsistent even when the main save loads. SaveEditor therefore separates file identification from Tool compatibility and only labels a game-specific Tool Verified when its exact profile/version evidence passes the runtime gate.
Where the format is stored
PC save locations: Windows: Steam: <Steam-folder>userdata<user-id>588650remote ; Microsoft Store: %LOCALAPPDATA%PackagesMotionTwin.DeadCellsWin10_rtjy889c6zgtgLocalCacheLocalMotionTwinDeadCells ; other desktop builds may use <path-to-game>save. Storefront context: Steam, GOG, Epic Games Launcher, EA app, Microsoft Store. The exact path depends strongly on storefront. Preserve both user_*.dat and customGameData_*.json if you want the same profile plus custom-game settings. This matters because two releases can use different containers or companion files even when the visible slot name is similar.
Back up before inspecting or editing
Copy the full active save directory, including user_*.dat and customGameData_*.json. On Steam, back up the complete 588650remote folder. A read-only viewer is lower risk than a writer, but the live save should still be copied first. Cloud context also matters: Steam Cloud, GOG Galaxy, Epic, EA, and Xbox Cloud are documented depending on edition. Keep the original bytes available so any experiment can be reversed without relying on a cloud service or automatic backup.
What this reference does not claim
This page does not infer an undocumented checksum algorithm, encryption key, compression layer, or cross-store conversion from the file extension. Troubleshooting evidence: If the wrong profile appears, check whether the game is using Steam remote, LocalAppData, or an install-folder save. Then compare timestamps before overwriting anything. Those questions require a verified parser/profile or a game-specific source, not a generic format guess.
Verification context: Reviewed against current PCGamingWiki Dead Cells save paths and file patterns.