Apps to Layer manipulation

GIMP (GNU Image Manipulation Program) is a powerful, free, and open-source raster graphics editor used for image manipulation, retouching, composition, and authoring. It supports a vast array of file formats and provides sophisticated tools comparable to commercial alternatives, making it a versatile choice for photographers, designers, and artists.

Gimp Painter is a discontinued fork of GIMP specifically enhanced with tools for digital painting and drawing. It aimed to provide artists with advanced brush capabilities and performance optimizations tailored for creative workflows on the GIMP platform.

LazPaint is a lightweight, portable raster image editor designed for simplicity while offering essential features like layers and various photo effects. It aims to be an accessible alternative to more complex software, making image editing approachable for users seeking a less overwhelming experience.

Seashore is a user-friendly, open-source image editor designed for Mac OS X, offering essential editing tools and layer support within a simple interface. It's based on the GIMP's technology and focuses on providing core image manipulation capabilities for casual users and hobbyists.

Krita is a powerful, free, and open-source painting program designed for professional artists and illustrators. It offers a comprehensive suite of tools for digital painting, sketching, image editing, and animation, making it a versatile solution for various creative workflows.