The signal-to-noise ratio (SNR) is a commonly used metric to evaluate image quality and radiofrequency coil performance in MRI. However, its calculation could be challenging. Here we introduce MR Optimum, a novel web-based application for the evaluation of SNR. By means of a user-friendly web GUI, readily available via any internet browser, it provides access to various methods for SNR calculation. The computing unit can be installed on a local server or distributed over the cloud. Results can be visualized, analyzed and exported in various formats. MR Optimum could help standardizing how SNR is calculated and reported in scientific publications.