Purpose <p>The silent substitution technique allows photoreceptor directed stimulation (i.e., the selective stimulation of different photoreceptor types or a specific combination of photoreceptor types).</p> Methods <p>Calculation of these stimuli is not trivial, requiring complex matrix calculations based on specific datasets (spectral power distributions of primary lights, photoreceptor fundamentals, and optical densities of pre-receptoral filters). Several tools have been published that facilitate these calculations, including an excel file and a python library, but these are difficult to use without prior knowledge.</p> Results <p>We introduce an online application that allows calculation of silent substitution stimuli in a graphical user interface (GUI) for common use-cases (3 to 5 primary lights, periodic stimuli modulated around an average setting of the test field, 10° standard observers).</p> Conclusion <p>The goal is to provide a practical tool that can be used in these cases, but that can also be used as a teaching tool for beginners who plan to use the more sophisticated methods.</p>