Factorio is straightforward to archive because each world save is itself a ZIP file, but the surrounding mod environment still matters. A user can copy one .zip and preserve the map bytes, yet later discover that required mods or versions are missing. SaveEditor recommends backing up the saves directory together with mod/version notes and checking whether the installation is standard or portable before assuming %APPDATA% is authoritative. The page deliberately separates ZIP structural validity from the game-level compatibility of the serialized factory.
Known Factorio save-file structure
The researched filename or folder pattern is Save games are ZIP archives, normally named <save-name>.zip.. File-extension context: .zip The documented format notes are: Factorio’s standard user-data directory keeps saves as zip files. The archive contains the serialized map/state needed by the game, and the application directory can be relocated in portable/custom setups.
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 save can load differently or fail when required mods/versions are absent. The fact that the file is a valid ZIP archive does not guarantee semantic compatibility with another Factorio environment. 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: %APPDATA%Factoriosaves. Storefront context: Steam, GOG, standalone. The default Windows root is AppData/Roaming, but ZIP/portable installations can use a local game data directory according to Factorio configuration. 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 entire saves directory and, for important modded factories, also preserve the mods folder and mod-list/version context. Keep the original .zip extension and avoid unpack/repack cycles unless required by a known workflow. 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 and GOG Galaxy cloud are documented. 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 a save is missing, verify whether the installation uses the standard user-data directory or a portable/custom write-data path. If loading fails, compare Factorio and mod versions. Those questions require a verified parser/profile or a game-specific source, not a generic format guess.
Verification context: Reviewed against the current official Factorio Wiki application-directory documentation and PCGamingWiki save path.