What is a RAR file?

A RAR file (.rar) is a compressed archive format that bundles many files and folders into a single, smaller file. Like a ZIP, it is a container you open to get the originals back, but RAR is its own format — not a ZIP — and it is known for squeezing files smaller than ZIP typically does.

RAR stands for Roshal ARchive, named after its creator Eugene Roshal. The reference program is WinRAR, made by RARLAB. The format has two generations in the wild: the older RAR v4 and the current RAR v5 (released 2013). Both start with the same magic bytes, Rar!\x1a\x07, which is how a program can recognise a RAR from its first few bytes without trusting the file extension.

You can open a RAR right here in your browser with ZipTool: drop a .rar onto the page and it is decoded entirely on your device — the file is never uploaded to a server. You can browse the archive, search by name, and preview text, images, audio, video, and PDFs inside it without extracting anything to disk. For the dedicated browser workflows, see extracting a RAR online and the online RAR viewer.

RAR vs ZIP: what is different

ZIP and RAR solve the same problem — pack many files into one compressed file — but they differ in a few practical ways. RAR usually achieves a better compression ratio than ZIP’s default DEFLATE, especially on text-heavy or repetitive data, because RAR’s compression algorithms are more aggressive. The trade-off is speed: RAR takes more CPU to create and extract than a plain ZIP.

The bigger difference is openness. ZIP is an open standard anyone can read and write; every operating system can make a ZIP out of the box. RAR is proprietary. Only WinRAR and the official RAR tools can create RAR archives, while the unrar decoder that reads them is freely available — which is why so many programs can *open* RARs but few can *create* them. For a deeper comparison, see archive formats explained.

RAR also pioneered features ZIP gained later or still lacks: solid archives (the whole archive is compressed as one block for a better ratio), multi-volume (split) archives that span several .partNN.rar files, recovery records that repair minor corruption, and strong AES-256 encryption.

How to open a RAR file

On Windows, the native choice is WinRAR itself (free to try, nagware on expiry but fully functional for extracting). 7-Zip is a free alternative that reads RAR, though its RAR v5 support for some advanced features is limited. On macOS, The Unarchiver and Keka both open RAR files cleanly. On Linux, unrar is the command-line tool.

In a browser: open the .rar in ZipTool and browse its contents with nothing installed. The archive is decoded locally in your tab — there is no upload and no server copy. This is the fastest way to check what is inside a RAR you just downloaded before you commit to extracting it. The full step-by-step is in how to open a RAR file.

Windows: WinRAR (the reference tool) or the free 7-Zip for reading RARs.
macOS: The Unarchiver (free) or Keka; double-click to extract.
Linux: install unrar, then unrar x archive.rar to extract with paths.
In-browser: drop the .rar onto ZipTool to preview contents with no install and no upload.

What you can preview inside a RAR

Once a RAR is open in ZipTool, the entries render the same way they do for a ZIP. Source code and config files — JavaScript, TypeScript, JSON, Python, Markdown, HTML, CSS, and many more — open in a syntax-highlighting editor. Images, audio, video, and PDFs render inline. A ZIP stored inside the RAR can be opened as its own archive without leaving the page.

Because the decoding runs through a WebAssembly build of the unrar library entirely inside your browser, the moment you close the tab the data is gone. There is no upload step for it to persist anywhere. You can even disconnect from the internet after the page has loaded and browsing, searching, and previewing keep working.

Two RAR features ZipTool does not handle in-browser

Being honest about limits matters more than pretending they do not exist. Two RAR capabilities are not supported by the in-browser decoder:

Multi-volume (split) RARs — an archive split across several .part1.rar, .part2.rar, … files — cannot be reassembled in the browser, because each part is only a fragment of the whole. Open those in WinRAR or 7-Zip instead.

Password-protected entries inside an otherwise open RAR are listed by name but cannot be previewed without the password. The current viewer has no password prompt, so encrypted entries show an error rather than their contents. Everything else in the archive previews normally.

Is opening a RAR file safe?

A RAR is just a container — opening one to look at its contents is low-risk, whether in a desktop tool or in a browser. The risk is not in viewing, it is in what you do next. The real archive itself can be a delivery vehicle for malware, and a malicious file extracted and then run is still malicious.

Previewing a RAR in ZipTool is a privacy win, not a security guarantee: your file never leaves the browser, so there is no server-side copy, but client-side processing does not make a malicious archive harmless. Treat archives from untrusted sources the same way you always would, and read more in security and privacy.

Frequently asked questions

What is a RAR file?

A RAR (.rar) is a compressed archive format that packs many files and folders into one smaller file, created by Eugene Roshal and the WinRAR/RARLAB team. It usually compresses better than ZIP and supports solid archives, split volumes, recovery records, and AES-256 encryption. Only WinRAR and official RAR tools can create RARs, but the free unrar decoder lets many programs open them.

What does RAR stand for?

RAR stands for Roshal ARchive, after its creator Eugene Roshal. The format is developed and maintained by RARLAB, which also publishes the WinRAR application for Windows.

Is a RAR the same as a ZIP?

No. RAR and ZIP are separate formats. ZIP is an open standard that any tool can read and write and that operating systems handle natively. RAR is proprietary — only WinRAR and official RAR tools can create RAR archives — and it typically achieves a better compression ratio than ZIP, at the cost of more CPU time. Many programs can open (decode) RARs even though they cannot create them.

Can I open a RAR file online without uploading it?

Yes. ZipTool decodes a .rar entirely in your browser using a WebAssembly build of the unrar library, so the file is never uploaded to a server. Drop the RAR onto the page to browse its contents and preview text, images, audio, video, and PDFs inside it.

Why will my RAR file not open?

The common reasons: it is part of a multi-volume (split) archive and you only have one part, an entry is password-protected and the tool cannot supply the password, the download is incomplete or corrupted, or the file is not actually a RAR despite the extension. Check that you have all .partNN.rar pieces, confirm the file starts with the Rar! signature, and try a dedicated tool like WinRAR or 7-Zip if an in-browser viewer cannot read it.