ImageJ is described as 'Public domain, Java-based image processing program developed at the National Institutes of Health. ImageJ was designed with an open architecture that provides extensibility via Java plugins and recordable macros' and is a Image Editor in the photos & graphics category. There are more than 25 alternatives to ImageJ for a variety of platforms, including Windows, Mac, Linux, Web-based and Android apps. The best ImageJ alternative is Fiji, which is both free and Open Source. Other great apps like ImageJ are MIPAR, Icy Image Processing, Paraview and MountainsMap.