Files with bkp extension can be mainly found as older backup files from backup utilities and other programs.
BKP file extension - Backup
What is bkp file? How to open bkp files?
File type specification:
File extension bkp is used by various backup application for backups of files, hard drive images or CDs/DVD. Its not an universal file format.
Used for example in the urboVidion Dialog Designer, or Zaplots Zapback.