Opening JAR files

Did your computer fail to open a JAR file? We explain what JAR files are and recommend software that we know can open or convert your JAR files.

What is a JAR file?

The .jar file extension was developed by Sun Microsystems. Files with the .jar extension are compressed files that use the ZIP format in order to compress Java files. The files with the .jar extension contain Java classes and metadata. JAR files are often used by programs like Thunderbird, Firefox and SeaMonkey to store program add-ons and program themes.

JAR files can also be created to store files, much in the same way ZIP files are used. Files with the .jar extension can contain multiple files that have been compressed into a single folder or one large file that has been compressed to achieve a more manageable file size.