The best free file compression software
Why use file compression software?
The most common use of file compression is to reduce the size of files before sending them as a single attachment (via email or a tool like WeTransfer). Compression also lets you save drive space by reducing the size of files you only use occasionally, and enables you to encrypt or password-protect many files at once
Compression tools use a variety of methods to reduce file size. Some file types, such as JPG and MPG, are already compressed, so adding them to an archive won't reduce their size much - if at all.
Windows (from XP onwards) has a built-in compression tool, accessed by right-clicking one or more folders/files, and selecting 'Send to > Compressed (zipped) folder'. This is fine for very occasional use, but is very limited. It can only read and create ZIP files (there are dozens of other formats), it doesn't let you create multiple volumes of a particular size, can't repair damaged archives, and can't encrypt files. In fact, if you use it to compress an encrypted file, it will be decrypted when extracted.
It's therefore a good idea to have a third-party compression tool on hand, and with some available completely free and weighing in at just a few megabytes, there's no reason not to. These are our recommendations. Have we missed your preferred tool? Let us know in the comments below.
The ultimate lightweight compression tool - no frills and no strings attached
7-Zip isn't the most attractive program around, but it's so well designed that you won't miss the slick interfaces of its paid-for equivalents. You can locate files to be archived using a simple Explorer-style file tree, or drag and drop them into the main window.
It can pack and unpack 7z, XZ, BZIP2, GZIP, TAR, ZIP and WIM archives, and unpack AR, ARJ, CAB, CHM, CPIO, CramFS, DMG, EXT, FAT, GPT, HFS, IHEX, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, QCOW2, RAR, RPM, SquashFS, UDF, UEFI, VDI, VHD, VMDK, WIM, XAR and Z.
You can apply password protection to packaged archives and split them into volumes, which is handy for sharing particularly large archives. The only key feature it's missing is the ability to repair damaged archives.
Another excellent open source archiver. Larger than 7-Zip, but with more features
PeaZip is another open source file compressor, but with a few more features in a considerably larger package (around 10MB compared to 7-Zip's 1MB).
PeaZip's standard installation will make file associations and add context menu options automatically, which you might not want if you're trying it for the first time. Select 'Custom' if you want to make your own choices. Alternatively, you can use the 1.8MB portable version, which runs without being installed and won't make changes to your PC.
PeaZip can pack and unpack to 7z, ARC/WRC, SFX, BZ2, GZ, PAQ/LPAQ/ZPAQ, PEA, QUAD/BALZ/BCM, SPLIT, TAR, UPX, WIM and ZIP. It can also unpack ACE, ARJ, CAB, CHM, compound files (eg MSI, DOC, PPT, XLS), CPIO, DEB, EAR, ISO, JAR, LZMA, LZH, NSIS installers, OpenOffice's OpenDocument, PET/PUP, PAK/PK3/PK4, RAR, RPM, SMZIP, U3P, WAR, XPI, Z and ZIPX.
Its handy extra features include the ability to convert archive formats and test archives for errors. It can't batch compress or watermark images as some of the other tools here can, but can rotate and crop them for you.
A portable version of PeaZip is also available.
Incredibly user-friendly. An excellent choice if you're new to file compression
Zipware is wonderfully simple to use - simply choose 'New' or 'Open', choose your source file or archive, tweak a few optional settings and you're done.
It's free to use, but if you decide to stick with it, the website invites you to make a donation to support its development. The software itself doesn't nag you for money.
Its standout feature is integrated virus-scanning: if an archive is under 32GB, you can check it for threats with VirusTotal. This is unlikely to be of interest to power users, but is a helpful addition for anyone who's unsure about extracting downloaded archives (or who knows someone with a tendency to accidentally open such things).
Zipware can read ZIP, ZIPX, 7Z, RAR, RAR5, ISO, VHD, MSI, GZIP, BZIP2, TAR, CPIO, DEB, DMG, LZH, LZMA, LZMA2, PPMd, NSIS, RPM, UDF, WIM, XAR, XPI, CBR, CBZ, XZ and Z archives. It can create ZIP, 7Z and EXE archives.
4. Ashampoo Zip Free
Optimized for touchscreens, but promotion of paid-for features can be overbearing
Before you can install Ashampoo Zip Free (or any of the company's software), you must register for a free account using your email address. You'll be sent a free activation key, then prompted to create a profile including your name and date of birth, but you can skip this step.
Watch out for potentially unwanted programs when running the installer; we ended up with an unwanted price comparison tool on our test PC, which wasn't picked up by Unchecky.
Ashampoo Zip Free's main features are presented as Windows-style tiles, but here the free program's limitations start to show, with paid-for features like encryption and archive format conversion (which are included with open source tools) locked out until you open your wallet.
Ashampoo Zip Free redeems itself with a very clear interface, which has an optional touch mode with larger, tap-friendly icons. All of the key features are immediately obvious rather than hidden behind ribbons and menus. Interestingly, it also gives previews of files before you extract an archive. This happens automatically, so don't be alarmed if a music file begins playing on mouseover.
You aren't given many choices when creating archives; most of the interesting features come into play when you're unpacking and sharing.
5. WinZip (trial)
The original file compressor - updated for the Windows 10 generation
WinZip has been around since 1991, and although it isn't free after the 21-day trial period (and therefore isn't ranked here) its ubiquity in the early days of file archiving - before the feature was incorporated into Windows itself - make it worth including in the interest of comparison.
The full standard version of Winzip costs £31.14 (US$35.95, AU$47.94), with automatic upgrades available for an additional fee. It supports ZIP, TAR, GZIP, Compress, CAB, RAR, BZ2, LHA/LZH, 7Z, IMG, ISO, XZ, VHD and VMDK.
The interface is a clear drag-and-drop affair, with additional options including encryption, PDF conversion and image resizing. The latter is labelled 'image compression', but doesn't perform the same job as specialist tools like JPEGmini or PNGOptimizer. Once you've set your preferences, you can save them as a preset for future use.
The latest version of WinZip includes social media and cloud integration, making it a great choice if you often need to share multiple files. Mobile apps are also available for iOS and Android.
WinZip is a classic that's evolved with the times, but unless file-sharing forms part of your everyday work, open source alternatives PeaZip and 7-Zip provide all the functionality you need minus the price tag.
6. WinRAR (trial)
The only way to create RAR archives, WinRAR is designed for power users
WinRAR is another premium tool with a history extending back to the early 90s, making it a useful point of comparison for today's free alternatives.
After the 40-day free trial period, a single-user WinRAR licence costs €29.95 (about £23.24, US$33.54, AU$46.52).
The proprietary RAR format can only be created using WinRAR, but can be extracted by almost any other program. As with 7z, this makes it a good choice for file-sharing. RAR archives are also typically smaller than their ZIP equivalents.
WInRAR can unpack CAB, ARJ, LZH, TAR, GZ/TAR.GZ, BZ2/TAR.BZ2, ACE, UUE, JAR, ISO, 7Z, XZ and Z archives, and compress in RAR and ZIP formats.
WinRAR's appearance has remained largely unchanged over the years, with command line and simple graphical interfaces (custom themes are available, with an equally old-school feel). That doesn't matter though; this is a tool designed for power users.
Its efficiency is particularly apparent when faced with larger tasks, which it handles with aplomb. You can even set it to turn off your PC once it's finished creating mammoth archives (or dozens of smaller ones).