You downloaded something from the internet and it's a .rar file. Your computer has no idea what to do with it because no operating system includes RAR support out of the box. You need WinRAR, 7-Zip, or The Unarchiver. Welcome to the most successful honour system in software — WinRAR asks you to pay after 40 days, almost nobody does, and it keeps working anyway.
RAR typically compresses 10–30% better than ZIP and offers features power users care about: solid archives (treating multiple files as a single data stream for better ratios), recovery records (that can repair damaged archives), and multi-part splitting for files too large for a single download. The format was created by Eugene Roshal — the R-A-R stands for Roshal Archive — and somehow became a pillar of internet file distribution despite being proprietary.
7-Zip (free, open-source) opens RAR files on Windows. The Unarchiver (free) handles them on macOS. If you're creating archives to share with others, use ZIP — it's more polite. RAR is the format you encounter, not the format you choose, unless you specifically need its superior compression for large files.
Technical details
Full Name
RAR Archive
MIME Type
application/x-rar-compressed
Developer
Eugene Roshal / RARLAB
Magic Bytes
52 61 72 21
Safety
.rar requires caution. RAR files from unknown sources may contain malware. Scan contents before extracting.
What opens it
WinRAR
FREEWindows
7-Zip
FREEWindows
The Unarchiver
FREEmacOS
* Perpetual trial
FAQ
How do I open a RAR file?
On Windows, install 7-Zip (free) or WinRAR (free trial that never expires). On macOS, use The Unarchiver (free from the App Store). On Linux, install unrar from your package manager. Unlike ZIP, no OS handles RAR natively.
What is the difference between RAR and ZIP?
RAR compresses slightly better and supports recovery records (which can repair damaged archives). ZIP is universally supported without extra software. For sharing files, ZIP is more compatible. RAR is mainly used when maximum compression matters or when you are downloading files that someone else packed.
Do I actually need to buy WinRAR?
Legally, yes — after the 40-day trial. Practically, WinRAR famously continues to work after the trial expires, showing only a reminder dialog. 7-Zip is a completely free alternative that opens RAR files and creates ZIP/7Z archives.
Is WinRAR safe to download?
Only from the official site (rarlab.com). WinRAR is one of the most commonly impersonated programs — fake download sites bundle malware with it. Go directly to rarlab.com and nowhere else.