Bad Peggy has been discontinued. Similar apps include ExifTool, which is free and open source. Other options are ExifToolGUI and JHOVE. In total there are three Metadata Editors like Bad Peggy for Windows, Linux and Mac.
ExifTool is a platform-independent Perl library plus a command-line application for reading, writing and editing meta information in a wide variety of files.
Canada
Graphical user interface to ExifTool for reading and writing metadata in images.
Slovenia
EU
JHOVE is a file format identification, validation and characterisation tool. It is implemented as a Java application and is usable on any Unix, Windows, or OS X platform with appropriate Java installation.
