Pixel Art Studio - A purpose-built drawing tool for pixel artists
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
GIMP - GIMP is a multiplatform photo manipulation tool.
Pixel Studio - The Pixel Art Is Always Fun
Affinity Photo - Affinity is the imaging and design suite for creative professionals exclusively for Mac.