From https://www.hardocp.com/news/2019/03/12/firefox_send_free_file_transfer_service_featuring_encryption/ "Mozilla has announced Firefox Send is now available for use as a free file transfer service with built-in end-to-end encryption. Send allows users to safely and simply share files from any browser without having to worry about their private information existing in the cloud. Send will be available as an Android app in beta later this week. Users can set when their file link expires, the number of downloads, and whether to add an optional password for an extra layer of security ... " From Mozilla: We know there are several cloud sharing solutions out there, but as a continuation of our mission to bring you more private and safer choices, you can trust that your information is safe with Send. As with all Firefox apps and services, Send is Private By Design, meaning all of your files are protected and we stand by our mission to handle your data privately and securely. Haven't tried it yet myself, but it seems like you could uplink a beta, PM people the password, and get feedback by the same method, all anonymously.