Files with the .NCO extension contain backup of the data to be written on a CD or DVD compressed using standard ZIP compression algorithms. The data can also be encrypted using a 56-bit key and protected with a password.

NCO files are created using the Nero BackItup software, the successor of the Nero BackItUp & Burn. If the NCO file is not encrypted, it can be opened using a ZIP decompression tool, such as WinZip or Stuffit Expander - just change the extension to ZIP and extract the file.