Colormate handles color work inside the Blender shader graph, calculating color harmonies directly in Blender so copying and pasting hex codes or RGB values is no longer needed. It supports mathematical and perceptive harmony calculation in realtime, along with drag-and-drop color swatches.
The addon reads and writes several palette formats: .aco, .acb and .ase from Adobe, .gpl from Gimp, .kpl from Krita, and its own .csv. That lets you import and manage palettes from Photoshop, Illustrator, Krita and Gimp. Colors live in one of two libraries: the Scene Library saves with the .blend file, while the Persistent Library keeps colors across scenes and files.
Additional features include a Scratchpad tab with 12 swatches for frequently used colors, the ability to create ColorRamp nodes from library colors, and sorting the library by value from darkest to lightest. The panel can dock in the Node Editor and/or the 3D View. Colormate is licensed under GPL.