INSENSITIVE is an educational simulation tool of nuclear magnetic resonance (NMR) spectroscopy for up to 4 coupled spins 1/2 in isotropic solution. In four steps the program simulates the spin physics behind NMR experiment, from defining the spin system via manipulation of the spin state and execution of pulse sequences to processing of 1- and 2-dimensional spectra. At its core, it visualises common models of the spin state, both graphic and numerical, and allows to interact with them at various levels of sophistication. In addition to the statistical quantum mechanics of the system, the double cone of a spin 1/2 under the influence of a magnetic field can be shown to illustrate the transition from a single spin to a spin ensemble. The program comes with an extensive tutorial and no prior knowledge of a programming language or spectrometer software is required.

INSENSITIVE was written in C using the GTK-3 toolkit. It replaces the older code base written in Objective-C and using the Cocoa toolkit for macOS. It has been tested on several, modern Linux distributions, including Ubuntu, Fedora and SUSE, and can be compiled from source. It has also been successfully compiled and tested on Microsoft Windows 7, 10 and 11 as well as Apple macOS (confirmed to work on versions 10.14 and 12). Binary versions for Windows and macOS are available from GitHub for 64-bit Intel processors and can be run without installation by executing bin\insensitive.exe or Insensitive.app, respectively.