What is the DAR file format?
.dar is a Unix and Linux backup archive format designed as a modern replacement for GNU tar. Unlike tar, which was built for sequential tape access, .dar archives support random access to individual files through an end-of-archive catalogue - so you can extract a single file without reading the entire archive.
The format offers several capabilities that tar lacks: per-file compression (each file can use a different algorithm - gzip, bzip2, lzo, xz, zstd, or lz4 - selectable by filename pattern), differential and incremental backups with tracking of deleted files across backup series, built-in encryption (AES-256, Blowfish, Twofish, Camellia, or OpenPGP), configurable file slicing to spread large archives across multiple volumes, and per-file CRC integrity checking.
An archive consists of one or more slice files. Each slice begins with a 16-byte header (magic identifier, slice name, flags). Content is stored sequentially within slices; the catalogue (table of contents) is written at the end of the final slice to enable fast random-access extraction. All multi-byte integers are stored big-endian.
.dar archives are not compatible with tar or ZIP. The primary tools are the dar command-line program and the libdar shared library. A Python automation wrapper, dar-backup (GitHub: per2jensen/dar-backup), supports long-term archival rotation workflows. The format has been actively maintained since 2002; the current release series is dar 2.7.x.
Security & safety
RISK: LOWDAR is a backup archive format; contents are as safe as the files archived. If the archive is encrypted (DAR supports AES-256, OpenPGP), you need the passphrase/key to extract. Always verify integrity with 'dar -t' before trusting a backup. Archives from unknown sources should be extracted to an isolated directory and scanned.
Format details
in a nutshell- Disk ARchive (Substance DAR) - DAR is also used by the Substance framework (substance/dar on GitHub) as 'Reproducible Document Archive' - a different ZIP-based format for structured documents; unrelated to disk backups.
Programs that open DAR files
Windows1 app
dar (via WSL or Cygwin)
Open-source Install WSL2 with Ubuntu, then: sudo apt install dar. Use dar commands inside WSL terminal. 
macOS1 app
Linux3 apps
dar (command-line)
Open-source Extract: dar -x archive_basename (omit slice number suffix). List: dar -l archive_basename. Test: dar -t archive_basename.
DarGUI
Open-source Qt-based GUI for dar; open archive via File > Open, browse contents, extract selected files.
dar-backup
Open-source Python wrapper for automated long-term dar backup schedules; manages full/differential backup series. Technical details
deep spec| Container type | Proprietary slice-based binary archive (DAR format) |
| Byte order | Big-endian (all multi-byte format integers) |
| Per-file compression | Selectable per file or by filename pattern: gzip, bzip2, lzo, xz/lzma, zstd, lz4, or none |
| Encryption | AES-256, Blowfish, Twofish, Camellia, Serpent (symmetric); OpenPGP asymmetric signing also supported |
| File slicing | Archive splits into configurable-size slice files; each slice has a 16-byte header (magic, name, flags) |
| Catalogue location | End of final slice; enables random-access extraction of individual files without reading the whole archive |
| Backup modes | Full, differential, and incremental; deleted-file tracking maintained across backup series |
| Integrity checking | Variable-length CRC per file data; archive structure also protected by CRC |
| Format version | Versioned (dar5, darK06 etc.); dar 2.7.x is backwards-compatible with archives created by dar 2.4+ |
| Primary interface | dar command-line tool and libdar shared library |
| MIME type | application/x-dar |
| Associated OS | Linux, macOS, FreeBSD, other POSIX systems; Windows via WSL or Cygwin |
| Released | 2002 (first release) |
| Latest version | DAR 2.7.x (2023-2024; actively maintained) |
| Open standard | Yes · royalty-free |
| Specification | darbinding.sourceforge.net |
DAR conversions
Community Q&A
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