Aladin is described as 'Interactive sky atlas allowing the user to visualize digitized astronomical images or full surveys, superimpose entries from astronomical catalogues or databases, and interactively access related data and information from the Simbad database, the VizieR service and' and is an app in the education & reference category. There are more than 25 alternatives to Aladin for a variety of platforms, including iPhone, iPad, Android, Android Tablet and Windows apps. The best Aladin alternative is Stellarium, which is both free and Open Source. Other great apps like Aladin are Sky Map, KStars, Gaia Sky and Sky Guide.