For DST, first identify whether you are preserving local client state or a hosted Cluster_* world. Copy the complete cluster, including all shards, rather than one session file.
For this PC reference, the documented storage is Windows: %USERPROFILE%DocumentsKleiDoNotStarveTogether. The known file or folder pattern is client profile data and Cluster_* world/server directories. Together separates client data from cluster/server world directories. A hosted world backup should preserve the entire Cluster_* directory, including Master/Caves shards when present.
Backup guidance: Close Don't Starve Together, let the launcher finish any synchronization, then copy the complete documented save directory to a dated folder outside the live path. Preserve companion files rather than selecting only the newest-looking record. Steam Cloud can synchronize client data; dedicated/server-hosted clusters must be backed up at the host. Launcher and cloud context matters because The active Steam installation determines which local profile and cloud copy can overwrite the save. Identify the storefront and account before restoring files.
Compatibility and recovery should stay conservative. Treat saves as version-, storefront-, account-, and mod-sensitive unless the game or a separately verified migration workflow proves otherwise. A similar filename or extension is not evidence that two releases are interchangeable. If the expected progress is not visible, If progress is missing after a restore, confirm the active Windows account, storefront/profile, cloud state, and exact directory first. Restore the untouched backup before experimenting with individual files or older autosaves. SaveEditor.com only labels a game-specific editor as available when a separate linked Tool has a verified operational runtime; this reference page by itself is not an editor claim.