FileSender is an open source web application for sending files of any size, quickly and securely. The sender has full control over who receives and can access the files and for which period of time – as it should be. Currently, National Research and Education Networks (NRENs) from all over the world offer FileSender service to their research and education communities to exchange large files such as data sets. Healthcare facilities can use the application to exchange diagnostic imagery such as cardiograms or MRI images. Government agencies that need to exchange (privacy) sensitive data sets for example can use FileSender and rest assured the data will never fall into the wrong hands.