The DICHROWEB web server is an online platform designed for analyzing circular dichroism (CD) spectroscopic data to determine protein secondary structure. It provides a user-friendly interface that supports various input formats and data units, making it accessible to users with different levels of expertise. The server offers five popular algorithms (SELCON3, CONTINLL, CDSSTR, VARSLC, and K2d) and seven reference databases, allowing for the calculation of secondary structure content and graphical comparisons of experimental and calculated spectra. Key features include a goodness-of-fit parameter (NRMSD) to assess the quality of the analysis, and the ability to handle data from both conventional CD instruments and synchrotron radiation-based CD beamlines. The server also includes information pages, FAQs, and help sections to assist users in interpreting the results. Future developments aim to enhance the server with additional reference databases, specialized algorithms, and calibration tools.The DICHROWEB web server is an online platform designed for analyzing circular dichroism (CD) spectroscopic data to determine protein secondary structure. It provides a user-friendly interface that supports various input formats and data units, making it accessible to users with different levels of expertise. The server offers five popular algorithms (SELCON3, CONTINLL, CDSSTR, VARSLC, and K2d) and seven reference databases, allowing for the calculation of secondary structure content and graphical comparisons of experimental and calculated spectra. Key features include a goodness-of-fit parameter (NRMSD) to assess the quality of the analysis, and the ability to handle data from both conventional CD instruments and synchrotron radiation-based CD beamlines. The server also includes information pages, FAQs, and help sections to assist users in interpreting the results. Future developments aim to enhance the server with additional reference databases, specialized algorithms, and calibration tools.