Funtools is a "minimal buy-in" FITS library and utility package developed at the the High Energy Astrophysics Division of SAO. The Funtools library provides simplified access to a wide array of file types: standard astronomical FITS images and binary tables, raw arrays and binary event lists, and even tables of ASCII column data. A sophisticated region filtering library (compatible with ds9) filters images and tables using boolean operations between geometric shapes, support world coordinates, etc. Funtools also supports advanced capabilities such as optimized data searching using index files.

Because Funtools consists of a library and a set of user programs, it is most appropriately built from source. Funtools has been ported to Solaris, Linux, LinuxPPC, SGI, Alpha OSF1, Mac OSX (darwin) and Windows 98/NT/2000/XP. Once the source code tar file is retrieved, Funtools can be built and installed easily using standard commands.