Cryptomator
Multi-platform transparent client-side encryption for your cloud files
Cryptomator is a free and open source project that offers multi-platform, transparent client side encryption of your files in the cloud. It works with just about any cloud storage service; is totally transparent so you can work with your files how you normally would; and secure with a 256-bit key length AES encryption. It’s also simple and easy to use with no need for different accounts, key management, cloud access grants or cipher configurations.