Use Sfc.ContentDownloadHandlerFactory interface to call apex class when a file is downloaded in Salesforce.   Sample Code: public class ContentDownloadHandlerFactoryImpl implements Sfc.ContentDownloadHandlerFactory {     public Sfc.ContentDownloadHandler getContentDownloadHandler( List<ID> listIds, Sfc.ContentDownloadContext context ) {            Sfc.ContentDownloadHandler contentDownloadHandler = new Sfc.ContentDownloadHandler();                /* To Prevent downloading it from Mobile */        if ( context == Sfc.ContentDownloadContext.MOBILE ) {       … Continue reading How to call apex class when a file is downloaded in Salesforce?