Pixelorama, a free and open source 2D sprite editor, has been updated to version 0.6. In this release, the application got support for color palettes, multiple themes, image editing tools like color invert or desaturation, and more.
Pixelorama is a fairly new sprite editor made with the Godot Engine (a cross-platform, free and open source 2D and 3D game engine) using GDScript, ideal for creating pixel art. It runs on Windows, macOS and Linux.