BoxCryptor - Boxcryptor encrypts your sensitive files before uploading them to cloud storage services like Dropbox, Google Drive, Microsoft OneDrive, Box, and many others.
CarrierWave - Solution for file uploads for Rails, Sinatra and other Ruby web frameworks.
Cloudfogger - Easy and secure encryption for the cloud. Provides security for all cloud storage services like Dropbox, OneDrive and Google Drive.
Uppy - The next open source file uploader for web browsers
Mega - Secure File Storage and collaboration
tus.io - File Uploads