gretl is an open-source software application for compiling and interpreting data mainly for econometrics. The name is an acronym for Gnu Regression, Econometrics and Time-series Library. It has a graphical user interface and can be used together with X-12-ARIMA, TRAMO/SEATS, and R. It is written in C, uses GTK as widget toolkit for creating its GUI, and uses gnuplot for generating graphs. As a complement to the GUI it also has a command line interface.
gretl includes the possibility to output models as LaTeX files. Its own data format is XML, and it can also import Excel, Gnumeric, OpenDocument Spreadsheet, Stata, EViews, RATS 4, GNU Octave, Comma Separated Values, PcGive, JMulTi, and ASCII files. It can export to GNU Octave, GNU R, Comma Separated Values, JMulTi, and PcGive file formats.
gretl has been reviewed several times in the Journal of Applied Econometrics: GRETL: Econometric software for the GNU generation, GRETL: 1.6.0 and its numerical accuracy, Teaching undergraduate econometrics with GRETL There is also a review of gretl in the Journal of Statistical Software: gretl 1.7.3