Besides the theoretical definition of the scoring system and its application to QM8 to train a transferable functional predictor, we want to provide an easy-to-use and accessible web interface that could facilitate the choice of choosing the best functionals for a molecule by directly running DELFI and analyzing the results on a web application. The website, available at of four pages (Figure ). A first page includes a summary of the definition of the scoring system, and an interactive score calculator is available to insert customize values, helping the user to understand how the score is calculated and the weight of overlap between states, the difference in energy, and oscillator strength. A second page is dedicated to the analysis of the calculated scores for QM8, giving an overview on the distribution of scores on the training set of the model. A third page contains a plugin to run the prediction directly in the web application. There are two possibilities for the user: the first one is to enter a single SMILES manually and the 38 scores will be printed, or, alternatively, provide a list of SMILES can be provided and a dataframe (in csv) format will be generated and ready to be downloaded and/or analyzed. The analysis can be performed on the last page, where a customized dataset can be uploaded. Histrograms with the occurrences of each functional above a certain threshold, filtered histograms showing the recurrences of the most performing functionals, and correlation matrices can be easily visualized directly on that page. We Figure : Screenshot of the four pages available in DELFI web application strongly believe that this user-friendly application will increase notably the applicability of DELFI and be of support to chemists of all the range of computational expertise.