Fityk

{{Infobox software

| name = Fityk

| logo = Fityk.png

| logo size = 48px

| screenshot = Fityk screenshot.png

| screenshot size = 250px

| caption = Fityk 1.0.1 under Windows

| developer = Marcin Wojdyr

| released = {{Start date and age|2004}}

| latest_release_version = 1.3.1

| latest_release_date = {{Start date and age|2016|12|19|df=yes}}

| operating_system = Cross-platform

| programming language = C++

| genre = Curve fitting

| license = GNU GPL

| website = {{URL|fityk.nieto.pl}}

}}

Fityk is curve fitting and data analysis application, predominantly used to fit analytical,

bell-shaped functions to experimental data. It is positioned to fill the gap between general plotting software and programs specific for one field, e.g. crystallography or XPS.{{cite journal |last1=Wojdyr |first1=M. |title=Fityk: a general-purpose peak fitting program |journal=Journal of Applied Crystallography |date=1 October 2010 |volume=43 |issue=5 |pages=1126–1128 |doi=10.1107/S0021889810030499}}

Originally, Fityk was developed to analyse powder diffraction data. It is also used in other fields that require peak analysis and peak-fitting, like chromatography or various kinds of spectroscopy.{{cite journal |last1=Wojdyr |first1=M. |last2=Gierlotka |first2=S. |last3=Palosz |first3=B. |title=FITYK – peak-fitting software with support for powder patterns analysis |journal=Acta Crystallographica Section A |date=26 August 2004 |volume=60 |issue=a1 |pages=s246 |doi=10.1107/S010876730409511X|doi-access=free |bibcode=2004AcCrA..60Q.246W }}

Fityk is free and open source, distributed under the terms of GNU General Public License, with binaries/installers available free of charge on the project's website. It runs on Linux, macOS, Microsoft Windows, FreeBSD and other platforms. It operates either as a command line program or with a graphical user interface.

It is written in C++, using wxWidgets, and providing bindings for Python and other scripting languages.