GIMP - GIMP is a multiplatform photo manipulation tool.
CODIJY Pro Photo Colorization - Add colors to black & white photos and recolor images with surprizing ease!
Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
Picture Colorizer - Colorize black and white photos on Window with AI technology
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
AKVIS Coloriage - AKVIS Coloriage manipulates colors of an image: from colorizing old black and white photos from your family archive to replacing colors in your color photos.