TrueCrypt is an open source software to encrypt volumes of data. It even supports the creation of virtual encrypted volumes which is portable. Developed by TrueCrypt Foundation
License: Open Source
TrueCrypt is an open-source disk encryption software known for its strong encryption and cross-platform support but is no longer actively maintained. In contrast, BoxCryptor Classic is a user-friendly solution with file sharing and cloud integration capabilities, albeit not open-source, making it more suitable for collaborative use cases.