Lorikeet
Are you a fan of computer graphics from the olden days of video games, before artists had the full gamut of 16,777,215 colors to play with and were instead constrained to palettes of up to 256 colors to choose from? Do you wish you could achieve fancy artistic effects by simply replacing colors in the palette of a single sprite? Do you wish this effect could be performed blazingly fast, and easy to combine into other shaders to boot? That's what Lorikeet is for!
One sprite, multiple palettes.
There are two parts to Lorikeet: the GML extension, and the editor tool.