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.
Try a universal file viewer
File.org aims to be the go-to resource for file type- and related software information. We spend countless hours researching various file formats and software that can open, convert, create or otherwise work with those files.
If you have additional information about the JAR file format or software that uses files with the JAR suffix, please do get in touch - we would love hearing from you.