GNU Regression, Econometrics and Time-series Library provides a library which comprises various functions relating to econometric estimation, a command-line client program and a GUI. The library is based on the stand-alone command-line econometrics program ESL, originally written by Ramu Ramanathan of the Department of Economics at UC-San Diego. The interfaces offer several least-squares based estimators. Besides reading data files in its own format it also reads RATS 4 databases. It has a built-in spreadsheet for editing data, and uses gnuplot for graphing. It can output regression results in LaTeX format.