Conversion of jar files to zip file format

You can simply decompress JAR files using Java, and then repack the content to a ZIP archive and this will essentially achieve jar to zip conversion. The actualy use of such conversion (repacking) is somewhat questionable thought and perhaps it's meant just as further compressing.

Open JAR file    Open ZIP file

Related software

7-zip icon

7-zip

Popular open source file archiver with a high compression ratio

FilZip

A freeware file compression tool

iPack icon

iPack

A full-featured compressed archives manager