Fritzing supports export to several graphics formats, including JPEG pictures, but this will only create raster image of the content and you can access this function under the File ► Export menu in Fritzing. The preferred output option is to vector graphics formats, because the content is usually vector based. It is unlikely any other tool can be used to export .fzz files this way, so using the original software is your only option for fzz to jpg conversion.
Updated: April 24, 2023