Convertio is a free file converter that lets you convert JFIF to JPG, PNG, HDR, PDF, ICO, PSD, WEBP, etc., formats. It lets you batch convert your JFIF images at once.

Browse to the JPEG file that you want to convert, then double-click the file to open it. If necessary, use the tools in the toolbox at the right side of the window to make any changes.