GIMP
GIMP is one of the best Photoshop alternatives you can find online. Granted, its user interface could definitely use an update, but with all the features you get for free, it’s worth adjusting to GIMP’s UI.
What makes GIMP stand out is that it’s completely free. The app was made by a collaboration of university students, hobbyists, and open-source software enthusiasts who aren’t out to get your money. Not only is the software free, but the team behind GIMP also offers dozens of tutorials you can access for no extra cost.
Of course, you can donate something to help them out or simply as a way to say thanks for providing such a powerful tool for free.