Gamemaker 8 Decompiler Link — Newest & Safe
Several developers have uploaded decompilation scripts as "educational source code." Look for repositories named GM8Decomp or gm8-reverse . These require you to compile the tool yourself using Python or C#, but they are free of malware.
Sometimes, external data files (included files) are not packed into the .exe and will be missing from the decompiled project. gamemaker 8 decompiler link