GIMP is described as 'free program for such photo retouching, image composition and image authoring. Essentially it's the closest thing to Photoshop you can get for free' and is one of the leading apps in the Photos & Graphics category. There are more than 100 alternatives to GIMP for a variety of platforms, including Windows, Mac, the Web, Linux and iPhone. The best alternative is Krita, which is both free and Open Source. Other great apps like GIMP are Paint.NET (Free Personal), Adobe Photoshop (Paid), Affinity Photo (Paid) and Pixlr (Freemium).