Open BAK File

Information, tips and instructions

Open BAK File

BAK file extension is typically used for various types of backup files or reserved copy files. BAK files could be produced by different applications and could range from a single file backup to a whole disk or a database backup.

Typical way how BAK file is produced is with auto save procedure. When application saves recent changes to a data to a storage device it renames older version of the file to a file with a BAK extension to make sure that if application crashes during saving process the information is still intact. This way even if there is a crash during a save process it will still be possible for application to restore a previous version with minimal data loss. Typically, auto save happens after relatively short period of time to prevent significant data loss.

Usually it is not possible to open BAK file in Windows or Mac OS just by double clicking on it. In order to open it you will need to find out which application created it and change BAK file extension to an extension which was used before information was backed up. For example, if the original data file was TXT and it was renamed or copied to a BAK file with a purpose of a backup you will need to change it extension back to TXT before you can open it.

Sometimes instead of completely changing file extension, BAK file extension is just appended to the end of the original file. This makes it easier to later open BAK file by restoring it to the original state because the original extension is known, and you don’t need to guess it.

If you don’t know an application which created BAK file but still need to open it, you can try to guess it. For example, you can infer the application from the file name or from the location of a file. Another way to guess an original file extension is by renaming a file to TXT and opening it with a text editor. Frequently data format signature is located at the beginning of the file and it may be possible to infer what the file is about by looking at it. Even though it is not always the most convenient way to open BAK file it could be the only one which works in such a case.

Open BAK File on Windows OS

  • Try double clicking on a BAK file in Windows File Explorer.
  • If the BAK reading software is associated correctly then the file will open.
  • If the file did not open and BAK file originated from Microsoft SQL Server backup you should follow Microsoft SQL Server backup restore guide to restore BAK file to the corresponding database.
  • To open BAK file of unknown origin use one of the hex editors (HxD, WinHex, UltraEdit, Sublime) to view what is inside the file to figure out what type of content is stored in BAK file.
  • Change BAK file extension to the one which corresponds to its contents.