BoxCryptor - Boxcryptor encrypts your sensitive files before uploading them to cloud storage services like Dropbox, Google Drive, Microsoft OneDrive, Box, and many others.

Cloudfogger - Easy and secure encryption for the cloud. Provides security for all cloud storage services like Dropbox, OneDrive and Google Drive.

Mega - Secure File Storage and collaboration

Tresorit - Encrypted cloud storage for your confidential files. Using Tresorit, files are encrypted before being uploaded to the cloud. Start encrypting files for free.

Google Drive - Access and sync your files anywhere

Nextcloud - With Nextcloud enterprises host their own secure cloud solution for storage, collaboration & communication from any device, anywhere.