Fitswork is described as 'windows image processing program, mainly designed for astronomic purposes. It contains batch processing, histogram functions, many filters, etc. Fitswork works entirely in floating-point arithmetic' and is an app in the Education & Reference category. There are three alternatives to Fitswork for Windows, Linux and Mac. The best alternative is DeepSkyStacker, which is free. Other great apps like Fitswork are Siril (Free, Open Source) and IRIS (Free Personal).
DeepSkyStacker is a freeware for astrophotographers that simplifies all the pre-processing steps of deep sky pictures. Registering / Stacking / Simple post-stacking processes to quickly view the final result.