CryFS encrypts your files, so you can safely store them anywhere. It works well together with cloud services like Dropbox, iCloud, OneDrive and others. Easy to setup and works with a lot of cloud storage providers. It runs in the background - you won't notice it when accessing your files in your daily workflow. Your data only leaves your computer in encrypted form. File contents, metadata and directory structure are all secure from someone who hacked your cloud. Released under LGPL.
Can be used locally but that's not its primary use case.
Two directories: A basedir that holds the encrypted files, and a mountdir which you interact with. The basedir is what gets stored remotely, synced, or whatever. Note: Not safe for concurrent access!
Files are split into equal size blocks, encrypted individually. Metadata and directory structures are also represented as those blocks for obfuscation. Block cipher used, random key generated, key encrypted with passphrase.
In Apt, Pacman, Homebrew, Nix repositories.
Default encryption algorithm: XChaCha20-Poly1305, scrypt for key derivation.
Github: https://github.com/cryfs/cryfs