Is WinZip compatible with older versions of WinZip and other Zip file utilities?

The short answer to the question posed in the title is Yes, the current version of WinZip is compatible with older WinZip versions and other Zip file utilitites.

You must consider certain factors when you create Zip files, however. To insure compatibility, using Legacy compression is the safest. If you are sharing your Zip files with others, it is recommended that you find out what Zip file utility they have installed. You may want to avoid using AES encryption when you are not sure.

Advanced compression methods and AES encryption are extensions to the Zip file format. Although WinZip has published the specifications for these format extensions, not all Zip file utilities have adopted them.

WinZip provides several methods for compressing the files that you add to a Zip file. In making a choice of compression method, you should determine whether you will be sharing your Zip file with others as mentioned above. Also, there are several other things to consider including, the type of data you are compressing, your plans for later unzipping the data, and the amount of time you are willing to wait while your data is being compressed.

The Settings tab in the WinZip ribbon interface displays the two basic zipping choices set two their default compression methods. These compression methods are also available in the Legacy menus/toolbar interface.

• .Zip: This option allows you to select one of four Legacy compression settings used to create a .zip file. These settings provide good, fast compression, compatible with most Zip file utilities. You may want to choose this option if speed of compression is a primary concern or if you are sending Zip files to others (and their Zip file utility is not known). Compression settings available for .Zip are:
• Maximum
• Enhanced Deflate
• Super fast
• No compression
• .Zipx: This option causes WinZip to create a .zipx file. Like the .zip option, this option allows you to choose one of four compression methods, however in this case they are advanced compression methods. The default is Best method. When using Best method, WinZip chooses a compression method for each file being zipped based on its file type. You may want to choose one of this or another of the advanced compression options if file size is a primary concern. If you are planning to share these files with others, you should be sure that they are using WinZip 12.1 or later. Jpeg compression and WavPack compression are only available when using Best method. Advanced compression settings available for .Zipx are:
• Best method
• BZip
• LZMA
• PPMd

Note: When creating .zipx files, you also have the option to use a Legacy compression method.

When considering compatibility of the Zip files you create with WinZip, you should also be aware of these two additional extensions to the Zip file format.

• AES encryption (128- and 256-bit key): AES encryption provides much greater cryptographic security than the traditional Zip 2.0 encryption method used in earlier versions of WinZip. WinZip's AES encryption (FIPS-197 certified) uses the Rijndael cryptographic algorithm which, in 2001, was specified by the National Institute of Standards and Technology (NIST) in Federal Information Processing Standards (FIPS) Publication 197 as the Advanced Encryption Standard (AES).
• 64-bit extensions: The Zip 2.0 format imposed restrictions on how large a Zip file could be, and the number of files it could contain. For all practical purposes, the 64-bit extended format eliminates all these restrictions. Using the extended format, the member file size, Zip file size, and number of member files you can add to a Zip file are limited only by your system's resources. WinZip uses the 64-bit extended format; however, only when the limits of the original format are exceeded. (The original Zip file format limited the number of member files in a Zip file to 65,535, and the maximum size of both the Zip file itself and any member file to 4 gigabytes.)

Please email Technical Support if you have additional questions.