gpatch

Compare and patch program for binary files. Builds one difference file for multiple files, patches can be applied recursive. This is the open source version of the former Amiga project GPatch.
The difference file format is very efficient, but it uses 32 bit pointers (the program is from the 90s), so it works not for large files.
A detailed description can be found in the Aminet (util/misc/gpatch.lha).