The monitoring of chemical reactions on the fly conducted in flow through the use of benchtop NMR spectroscopy is an emerging field of research allowing tremendous perspectives. In-line benchtop NMR enables diversified structural and quantitative data on the chemical composition to be obtained and determination of reaction conversions, kinetics and mechanisms. This review provides an overview of the state-of-the-art of flow reactors integrating in-line monitoring with benchtop NMR spectrometers. A brief discussion on the main characteristics of benchtop NMR and associated recent technological developments is provided in the section after the Introduction.