Cryptomator Cloud Encryption

Cryptomator is a free and open-source encryption tool designed specifically for securing files stored in cloud storage services. Developed by Sebastian Stenzel (skymatic) and first released in 2014, the project is maintained by Skymatic GmbH, a company based in Bonn, Germany. Cryptomator was created to address the privacy gap in cloud storage: while services like Dropbox, Google Drive, and OneDrive store files on remote servers, they can still access user data. Cryptomator ensures that only the user can decrypt their files, even if the cloud provider's servers are compromised. Key features: transparent encryption: creates virtual drives (vaults) on the local system. Files dropped into a vault are automatically encrypted before being synced to the cloud storage. The encryption is transparent: open the vault with a password, and the files appear in their original, unencrypted form locally. Close the vault, and everything is encrypted again. AES-256 encryption: each file is individually encrypted using AES-256-GCM (Galois/Counter Mode), providing both confidentiality and integrity. Each file gets a unique key, and file names and folder structures are also encrypted. Cloud integration: works with any cloud storage service that synchronizes a local folder, including Dropbox, Google Drive, OneDrive, iCloud, Mega, WebDAV, and self-hosted Nextcloud. No account or registration required. Cross-platform: desktop versions for Windows, macOS, and Linux. Mobile apps for iOS (since 2019) and Android (since 2020). Vault format: versioned vault format ensuring forward compatibility. The vault structure consists of encrypted files with randomized names in a masterkey-protected directory. Key derivation: the master key is derived from the user's password using scrypt (a memory-hard key derivation function) with high iteration counts to resist brute-force attacks. Honorable mention at European IT Prize. Donation-ware model. Java/Kotlin. MIT (desktop), proprietary (mobile).