3.6 | 7 Votes
What is a BAK3 file?
The "bak3" extension may be used to represent the third backup version for a file. Every time you save a scene in Vue, another BAK file is created. The "bak3" extension would be used on the third save. You can choose the maximum amount of backups you want created by using the "Max backups" setting in Vue.
Another use of the "bak3" extension is to backup a BAK2 file that backs up .CRY map level files. If your CRY file is corrupt, you can replace it by renaming the "bak3" extension of your file to "cry."
Programs that open BAK3 files
Starbound Backup File
3.5 | 2 Votes
A BAK3 file may also be a backup file used by Starbound, an open, sandbox 2D space exploration game. It stores backup information for the game, which may be about a spaceship or player character. BAK3 files are helpful for recovering information in the event of a computer crash or corrupt SHIPWORLD or PLAYER file.
BAK3 files are named with the ".bak3" extension added to a PLAYER or SHIPWORLD file. For example, if the file is storing backup information for a SHIPWORLD file, the filename would be ab 07704dbcb4162646d4d93bbeef34df.shipworld.bak3.
You can delete the ".bak3" extension from the filename and open the file as a SHIPWORLD file in Starbound. However, it is important that you do not change the string of characters preceding the extensions.
BAK3 files can be found in the "player" folder in the "Starbound" folder. For example if you purchased Starbound through Steam, the BAK3 files are stored in the following location in Windows: