RAR

A proprietary lossless archive format created by Eugene Roshal, known for higher compression ratios than ZIP, built-in error-recovery records, and the ability to split an archive across multiple volumes.

Extension

.rar

Full name

Roshal Archive

Introduced

1993

Vendor

Eugene Roshal / win.rar GmbH (RARLAB)

What is inside the container

A RAR archive bundles and compresses files using Roshal's proprietary algorithm (a mix of LZSS-style dictionary compression and range/PPM coding depending on version), and unlike ZIP's per-file compression, later RAR versions can apply solid compression across the whole archive for better ratios on many small similar files. It supports multi-volume splitting (the classic .r00, .r01… or .part1.rar, .part2.rar sets), optional recovery records that let a slightly corrupted archive still be repaired, and AES-256 encryption — but only the decompression algorithm is openly published, while the compression algorithm itself remains proprietary to RARLAB.

How to open it

Windows WinRAR (RARLAB's own tool, free to evaluate, paid license for continued use) or 7-Zip (extraction only)

macOS The Unarchiver or Keka, both free, since macOS has no built-in RAR support

Linux unrar (RARLAB's free command-line extractor) or the open-source unar for extraction; creating new RAR archives requires the non-free rar tool

DAM/asset pipeline RARLAB's official unrar library/CLI, wrapped in a server-side script, extracts RAR contents for indexing since no fully open-source implementation of the compression side exists

For archives

RAR is not a recommended long-term archival format for a DAM: its compression algorithm is proprietary and only RARLAB controls the specification, so there's no guarantee of universal, license-free support decades out, unlike ZIP or the open 7z/gzip formats. If a DAM receives assets bundled as RAR, extract and re-catalog the individual files (and re-archive as ZIP or 7z if bundling is still needed) rather than keeping RAR as the storage format.

Eugene Roshal, a Russian software engineer, created the RAR format in 1993 — the name literally stands for Roshal Archive — and followed it with the WinRAR graphical archiver in 1995. RAR was built to beat ZIP’s compression ratio, and its later versions added features ZIP lacked at the time, including solid compression across an entire archive, recovery records that can repair a partially damaged file, and clean multi-volume splitting for distributing large archives across many smaller parts. Licensing sits in an unusual arrangement: Eugene Roshal’s older brother Alexander holds the copyright to the RAR compression algorithm, while win.rar GmbH licenses the WinRAR software itself, and RARLAB publishes the decompression code for others to use — but the compression algorithm stays proprietary and off-limits to reimplement.

In a DAM, RAR mainly shows up as an inbound format — assets a client, vendor, or archive downloaded from elsewhere arrive bundled in — rather than something a DAM should produce or store natively. Because no operating system ships built-in RAR support and the compression side of the format is closed, a DAM ingest pipeline typically shells out to RARLAB’s own unrar extractor to unpack RAR contents, catalogs the individual files, and then discards or archives the original RAR only for provenance, since it offers no long-term advantage over an open archive format like ZIP or 7z for storage.

Frequently asked

Why doesn't Windows or macOS open RAR files natively?

RAR is a proprietary format owned by win.rar GmbH; unlike ZIP, its specification and creation tooling were never released for free reimplementation by OS vendors, so both platforms require a third-party tool like WinRAR, 7-Zip, or The Unarchiver.

Is it free to extract RAR files, even if creating them isn't?

Yes: extracting RAR archives costs nothing. Free tools such as 7-Zip, the freeware UnRAR utility, and PeaZip can all decompress RAR content at no cost. Creating or compressing files into RAR is different: that requires a paid WinRAR or command-line RAR license once the 40-day evaluation period ends, after which the program keeps running but nags for purchase. This read/write asymmetry exists because RARLAB freely distributes decompression code but keeps the compression algorithm itself proprietary and commercially licensed.

Should a DAM store assets as RAR archives long-term?

No — because the compression algorithm is proprietary and controlled by one company, RAR carries more long-term-support risk than open formats like ZIP or 7z; extract and re-catalog RAR contents rather than keeping RAR as the storage format.

What does RAR do better than ZIP?

RAR generally outperforms ZIP on the same content because it uses a more modern compression algorithm with solid-archive mode, squeezing files noticeably smaller than ZIP's older Deflate method. It also adds error-correction: a recovery record can be embedded during creation, letting WinRAR reconstruct a partially corrupted archive that ZIP simply can't fix. Multi-volume splitting is built in too: RAR breaks large archives into fixed-size parts, or the classic .r00/.r01 sequence, without needing third-party tools, something ZIP only manages through workarounds.

Can a corrupted RAR archive still be opened?

Sometimes — if the archive was created with a recovery record enabled, WinRAR can repair minor corruption; without one, a damaged RAR archive may be partially or fully unrecoverable, same as any other archive format.

What are the .r00, .r01 files that sometimes come with a RAR archive?

Those are the classic multi-volume RAR naming scheme (older format), splitting one large archive into numbered parts; newer WinRAR versions instead use .part1.rar, .part2.rar naming for the same purpose.

Who actually owns the RAR compression algorithm?

Eugene Roshal, a Russian software engineer, created the RAR format in 1993 and gave it its name: RAR literally stands for Roshal ARchive. Today the rights are held commercially by win.rar GmbH, the German company that licenses WinRAR and the RAR compression technology; documentation lists Eugene's brother Alexander Roshal as the registered copyright holder. Unlike ZIP, an open documented standard, RAR stays proprietary and closed: its algorithm isn't published, and license terms explicitly forbid reverse-engineering it.

Can RAR archives be password-protected and encrypted?

Yes — WinRAR supports AES-256 encryption for both file contents and, optionally, the archive's file list/headers, which is stronger than the legacy ZipCrypto scheme still found in many ZIP tools.

Sources

The RAR format was developed in 1993 by Eugene Roshal; the name stands for Roshal Archive, and he released the WinRAR graphical archiver in 1995. checked 2026-08-07 — Wikipedia — RAR (file format)
RARLAB publishes and permits redistribution of decompression (unrar) code, but the license explicitly prohibits using that source to recreate the proprietary RAR compression algorithm. checked 2026-08-07 — HandWiki — RAR (file format)