Name: Seashore

Platform: Mac

Download Links: 
https://sourceforge.net/projects/seashore/files
Download in the macOS App Store
itunes.apple.com/us/app/seashore/id1448648921?mt=12

Description:
Seashore is a raster graphics image editor for macOS. Seashore is based on GIMP and is designed to be a simple to use image editor native to macOS. Seashore supports TIFF, PNG, GIF, and JPG image formats. XCF, GIMP’s format, is used naively by Seashore. Files made by Seashore can be opened and edited in GIMP. Seashore is similar to Paint.NET for Windows.