What is the NCO file format?
An .nco file is a Nero BackItUp Compressed Backup File - an archive format associated with Nero BackItUp, Nero AG's backup utility bundled with Nero Multimedia Suite and Nero Burning ROM packages. .nco archives are typically used for storing backed-up data, with optional password protection using Nero's proprietary 56-bit encryption. Unencrypted .nco files use standard ZIP compression and can be opened with any ZIP tool such as 7-Zip or WinZip.
.nco files are chiefly used to store data backups. Nero BackItUp allowed users to create backups with minimal configuration, originally targeting CD and DVD as backup media. CD and DVD have since been displaced by portable storage devices, and cloud storage has gained popularity as it allows access to data from multiple devices.
Nero BackItUp was discontinued around the Nero 12 era (circa 2012). Encrypted .nco files require the original Nero BackItUp software to decrypt - a significant limitation now that the product is no longer supported. Users preserving old .nco archives should export their contents while legacy Nero software remains accessible.
Security & safety
RISK: LOWNCO files are backup archives; the content risk depends on what was backed up. No known exploits targeting NCO format itself. Encrypted files require the original password.
Format details
in a nutshellPrograms that open NCO files
Windows4 apps
Nero BackItUp
Paid The original program for restoring NCO backups including encrypted ones. Current Nero versions may no longer include BackItUp; check nero.com for legacy downloads. 
7-Zip
Open-source Right-click → 7-Zip → Open archive (works for unencrypted NCO files only). Encrypted NCO will show garbled content or fail. 
Technical details
deep spec| Internal format | ZIP-based archive with Nero-proprietary metadata wrapper |
| Magic bytes (unencrypted) | 50 4B 03 04 - standard ZIP local file header (PK signature) |
| Byte order | Little-endian (ZIP structures) |
| Compression | DEFLATE (ZIP-based) |
| Encryption | Optional; proprietary 56-bit key - not compatible with standard ZIP AES encryption |
| Typical file size | 1 MB - several GB depending on backed-up data |
| Integrity check | ZIP CRC-32 per entry |
| Supported OS | Windows only |
| Encrypted file handling | Requires original Nero BackItUp software; incompatible with 7-Zip and WinZip |
| Unencrypted file handling | Standard ZIP archive; openable with 7-Zip, WinZip, or Windows File Explorer |
| Product status | Discontinued approximately 2012 (Nero 12 era) |
| Max entries | 65,535 (ZIP format limit) |
| Bundled with | Nero Multimedia Suite, Nero Burning ROM packages |
| Released | circa 2003 (Nero BackItUp 1.x) |
| Latest version | Nero BackItUp 4 / Nero 12 era (circa 2012); product discontinued |
NCO conversions
Community Q&A
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