This app is ad-supported to keep it free, but ads are not annoying and can be quickly closed or temporarily turned off in Settings. And there are no ads while editing!
You can do all the usual canvas or free layer manipulation such as resize, crop, drawing, erase, draw shapes, bucket fill, select, copy, paste, delete, move, align, rotate, flip and more.
Adjust brightness, contrast and saturation with filters or apply effects such as sharpen, blur, bump, shadow and many more. Undo and redo are available, and you can also save a set of actions and presets to re-apply them later.
Save your work with layers so you can continue editing later.