In field electron emission (FE) studies, it is important to check and analyse the quality and validity of experimental current-voltage data, which is usually plotted in one of a small number of standard forms. These include the so-called Fowler-Nordheim (FN), Millikan-Lauritsen (ML) and Murphy-Good (MG) plots. The Field emission orthodoxy test is a simple quantitative test that aims to check for the reasonableness of the values of the parameter “scaled field” that can be extracted from these plots. This is done in order to establish whether characterization parameters extracted from the plot will be reliable or, alternatively, likely to be spurious. This paper summarises the theory behind the orthodoxy test, for each of the plot forms, and confirms that it is easy to apply it to the newly developed MG plot. A simple, new, accessible web application has been developed that extracts scaled-field values from any of these three plot forms, and tests for lack of field emission orthodoxy.