LabPlot

Project-based, user-friendly alternative to commercial software for analyzing, fitting, smoothing data and making beautiful, publication-ready, themed plots. It's equipped with interactive notebooks for R, Python, Julia, Maxima and others. It supports a lot of file formats. A highly-recommended free gem!

Great and free application for professional graphs, plots, charts and function graphing :-) Descriptive statistics, curve fitting, distribution fitting, linear and non-linear regression, data smoothing and data extraction (plot digitizer), Fourier Transform (FFT) and Hilbert Transform... Check the application website to download development builds with greatly improved features.

Amazing interactive plotting and visualizing data quickly.

I've used LabPlot for a long time and it is a very good choice for a free, easy to do high-quality plotting, data analysis and statistics. It is fast and stable. There is support for live data and data extraction from plots. LabPlot allows you to export your data and plots to many formats (including text, image, LaTeX, PDF, PNG and others) and to import data from text, image, SQLite, SAS, Stata, SPSS, Origin, MATLAB, HDF5, netCDF, FITS, ROOT. Absolutely no programming is required, but you can use interactive Notebooks for your favorite programming language (Python, R, Julia, Maxima, Octave etc), if you need to. Did I mention that it's free and available for Windows, Linux and macOS? Sure, there is room for improvement, but the application is in heavy development, and the development team is really responsive and friendly. Definitely worth a try.