QtiKWS is the cross-compiled program designed for the graphical visualization, reduction, analysis, and fit of data produced by small-angle neutron scattering (SANS) instrument. Originally developed for use with the data from the SANS instruments of the Jülich Centre for Neutron Science (JCNS ) at FRM2 reactor in Garching (Germany), but most of functions could be used for any SANS instrument. QtiKWS is forked from the free software package qtiplot (v.0.8.9). QtiPlot is open source platform independent alternative to proprietary scientific software like Origin, SigmaPlot, Regressi or Igor Pro. The numerical routines have been written in C whereas the menu interface has been written in Qt/C++. GNU-licensed mathematical library GSL is used for the implementation of mathematical algorithms. Tables, matrixes, 2D and 3D graphs could be saved as a single project file and easy accessible by the built project explorer.

A standard way of SANS data reduction with limited number of options is implemented in “user-mode” of “DAN-light” plugin; while in “advanced-mode” a lot of different options and methods are active. Data reduction of all measured datasets in “5 minutes principle” is allowed due to step-by-step definition of two script tables, namely a table of conditions and sample table.

Fitting interface “FIT-1d” allows to an user to fit radial averaged datasets taking into account polydispersity of any parameter of a fitting function and/or the instrument resolution. Global fit algorithm has been implemented, which allows to simultaneously fit several scattering curves with a common set of parameters. “Set-by-Set” algorithm allows to start a fitting procedure of hundreds datasets in two mouse clicks. This option is especially important for time resolved measurements, when datasets should be analyzed in the same way. Powerful function simulator simplifies the estimation of initial fitting parameters and the presentation of the obtained fitting curve. Fitting of 2d-datasets has been implemented in “FIT-2d” interface. An advance of the fitting with qtiKWS is the runtime compilation of a fitting function. An user of this program has possibility to check code of the function, change , and recompile it as a new function. The user-friendly interface “FIT-compile” allows to create and compile any complex function. GSL numerical algorithms could be easily used in the function body. The fitting function is written in C, but there are implemented an option of calling of FORTRAN functions. Users simply download and run QtiKWS compiled for Windows and Linux computer platforms.