What is the BKP file format?
.bkp is a generic backup file extension. .bkp, along with .bak and .old, is a conventional suffix used to mark backup copies of files or folders. A backup copy of some_file.txt would typically be saved as file.txt.bkp - either an exact copy of the original file or a proprietary backup container written by the creating program. The added suffix usually prevents the file from being opened by other applications. The backed-up file can be quickly restored by removing the .bkp extension when it is a plain copy; for proprietary formats, use the original application's restore function.
.bkp is not a single format - Microsoft Money, Sage, SAP NetWeaver, mobile-phone backup tools, and code editors all use this suffix for their own incompatible structures. There is no fixed file header; use the file command or a hex viewer to identify an unknown .bkp.
Using this simple method of backing up files offers a straightforward way to safely modify file contents, as it provides an easy mechanism for recovery should anything go wrong during editing. This is especially useful when editing binary files with external tools, or when changes could have unexpected results. Some financial applications add password protection or compress their .bkp output internally, so the file may behave more like a ZIP archive than a plain copy.
Security & safety
RISK: LOWA .bkp is only as risky as the data it copies: a backup of a clean document is harmless, while a backup of a malicious file carries the same risk as the original. Don't blindly delete .bkp files until you've confirmed the live file is intact - a backup is often your only recovery copy. Scan an unknown .bkp if its origin is uncertain, and never rename a .bkp to .exe/.dll and run it without verifying its source.
Format details
in a nutshellPrograms that open BKP files
Windows4 apps
7-Zip
Open-source Inspect an unknown .bkp: try opening it as an archive, or check its first bytes to identify the underlying format. 
Original program (Restore / Import backup)
Built-in Open the application that created the .bkp and use its File > Restore / Import from backup command - the reliable method for app-specific backups.
Rename-back trick
Built-in If the .bkp is a plain copy, duplicate it and change the extension to the original's (e.g. .mdb/.txt/.docx), then open it in the matching program.
Notepad / any text editor
Open-source If the original was text/config, open the .bkp directly to read or copy out its contents. 
macOS2 apps
Original program (Restore / Import backup)
Built-in Use the creating app's Restore/Import command, or duplicate the .bkp and rename the extension back to the original type. 
Linux1 app
file + a text editor
Built-in Run file something.bkp to detect the real type, then open with the right tool (or cp file.bkp file.<orig-ext>). Technical details
deep spec| Format type | Generic backup suffix - not a single format; each application defines its own internal layout |
| MIME type | application/octet-stream (generic fallback; no MIME type specific to .bkp is registered) |
| File signature (magic bytes) | None fixed - the first bytes are determined entirely by the creating application |
| Encoding | Binary or plain text, depending on the source program |
| Compression | Varies - some applications (e.g., accounting software) compress their .bkp output; many do not |
| Encryption / password protection | Varies - financial and accounting backups are sometimes password-protected |
| Typical file size | A few KB to several GB - entirely dependent on what is being backed up |
| Byte order | Inherited from the underlying file format; no fixed endianness |
| Associated operating systems | Windows, macOS, Linux, Android (phone backup tools) |
| Common creating software | Microsoft Money, Sage, SAP NetWeaver, mobile-phone backup tools, code editors, installers |
| Restore method - plain copy | Rename the file back to its original extension (e.g., file.txt.bkp → file.txt) |
| Restore method - proprietary backup | Open in the application that created it and use its built-in restore or import function |
| Functionally equivalent extension | .bak - a more common backup suffix; both mean 'backup copy' with no structural difference between them |
| Checksum / integrity data | Varies - some backup formats embed a checksum or manifest; a plain file copy has none |
| Released | Convention; .bkp has been used as a backup suffix across PC software for decades |
BKP conversions
Community Q&A
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Frequently asked questions
How do I open a BKP file?
What is the difference between .bkp and .bak?
What program opens a BKP file?
file command.
