Whitehole
Whitehole is the successor to Anarchy in the Galaxy (sometimes just referred to as Anarchy). Both computer programs were developed as stage editors for the Super Mario Galaxy games, where Whitehole added many more features and built-in tools, and most notably, a 3D rendering of the stages (which Anarchy lacked).
Development for Anarchy began sometime in early 2010 or 2011, some even believe before the 2nd Galaxy game came out, by a user(s) known as/by (???). The tool gained popularity as the online Kuribo64 forums opened in 2012, which hosted many of the early Galaxy hacking scenes.
Whitehole wouldn't begin development until 2012, when its earliest builds would be released to Kuribo64's uploader.
From this day on; Whitehole, while other projects to replace it have occurred but all failed (Shibboleet's Takochu, and SuperHackio's Starlight, to name a few), still remains as the main stage editor for Galaxy hackers.
While many public repositories for Whitehole exist, the most current and maintained of these (as of the writing of this page) is the following: https://github.com/SunakazeKun/Whitehole-Despaghettification