GmapTool

GMapTool is a free program for splitting and merging maps in Garmin format. Its main function is to merge maps in img format and split files in img format into mapset, maps, and subfiles of maps.
The application also installs mapsets for use with programs like Mapsource, BaseCamp, and HomePort.

It is also able to edit map properties like map type, priority, transparency, name, and creation date, and modify maps, changing labels case, removing national characters, and replacing TYP files.

Windows version works with multiple languages. Additionally, command-line version gmt.exe can be used inside scripts for map processing.