What is the SAVE file format?
A .save file is a binary game save state created by id Software's id Tech 4 engine, used primarily in Doom 3 (2004). When the player saves their progress, the engine serializes the full world state - including the current map, player position and health, inventory, entity states, and script variables - into a .save file stored in the game's dedicated savegame folder.
The format is engine-internal and written in little-endian binary. Unlike text-based configurations or PK4 archives, .save files have no publicly documented file signature (magic bytes); the engine identifies them by their location in the save directory rather than by a header. A companion preview screenshot is written alongside each save entry so the game's save/load menu can display a thumbnail.
Save files are tightly version-locked: they are not portable between different builds or patches of the game, and editing them is unofficial and unsupported. On load, the id Tech 4 engine validates the file and rejects any corrupt or incompatible saves.
Beyond Doom 3, the same .save extension and engine format were used by other id Tech 4 titles including Quake 4 and Prey (2006). Open-source source ports such as dhewm3 can load original Doom 3 .save files on Linux and macOS.
Security & safety
RISK: LOWA Doom 3 .save is passive game data that only the game loads; it cannot execute on its own. Risks are practical, not malware: saves are tied to the game build (copying between mismatched versions can fail), and unofficial save editors can corrupt the file. Keep a backup before editing. Be wary of "universal save editor/converter" download sites, which are often adware.
Format details
in a nutshell- Generic application/game save state - Many other games and programs write .save files; format is entirely app-specific and only the originating program can read it.
- GNU nano emergency save (.save) - nano appends .save to a filename when it dumps a buffer on a crash; it is plain text, not a Doom save.
Programs that open SAVE files
Windows2 apps
Doom 3
Paid Launch Doom 3, choose Load Game, and pick the save. Saves live in the game's savegame folder. 
Doom 3 BFG Edition / RBDoom3BFG
Open-source Open-source rebuild of the engine; load saves from the in-game menu (BFG saves differ from classic ones). 
macOS1 app
Linux1 app
Doom 3 (dhewm3)
Open-source dhewm3 is a maintained Doom 3 source port; place saves in its save folder and Load Game. Technical details
deep spec| Format type | Binary game save state (engine-internal) |
| Developer | id Software |
| Engine | id Tech 4 |
| Byte order | Little-endian |
| Encoding | Binary |
| Compression | Largely uncompressed game-state blob; engine-dependent |
| Typical file size | 1 MB - 20 MB (level state plus entities and preview image) |
| File signature (magic bytes) | None documented; identified by location in the game's save directory |
| Stored contents | Serialized map name, player state, inventory, entity states, and script variables |
| Preview image | A companion screenshot thumbnail is written alongside each save for the in-game load menu |
| Version compatibility | Version- and game-build-specific; not portable across different patches or titles |
| Integrity checking | Engine validates the save on load; corrupt or incompatible files are rejected |
| MIME type | application/octet-stream |
| Associated platforms | Windows, Linux, macOS (via ports including dhewm3) |
| Games using this format | Doom 3 (2004), Quake 4 (2005), Prey (2006) - all on the id Tech 4 engine |
| Released | 2004 (Doom 3, id Tech 4 engine) |
| Latest version | id Tech 4 era (Doom 3, Quake 4, Prey 2006) |
SAVE conversions
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