Here you can download the Game Maker 8.x decompiler, created by x2048. Due to legal problems from YoYo Games, they had to pull it from their site. Several mirrors will be provided in the event that one or more is taken down. Please don't use this tool to steal others' code. Remember to check back here for updated / new decompilers when new GM versions are released!

Versions 5, 6, 7
Main download and website: Messy Mind
Mirror 1: here

Version 8.x
Main download link (this was not uploaded by me): Host-A
Mirror 1: here

These tools may be mirrored as long as the proper credits are given. If you create a mirror and would like it to be listed here, you can contact me.