VeraCrypt is a free disk encryption software brought to you by IDRIX and that is based on TrueCrypt . It adds enhanced security to the algorithms used for system and partitions encryption making it immune to new developments in brute-force...
Cryptomator provides transparent, client-side encryption for your cloud. Protect your documents from unauthorized access. Cryptomator is free and open source software, so you can rest assured there are no backdoors.
[TrueCrypt is not exactly "Open Source", but the source is available. See the reviews to get more information.]Discontinued
The development of TrueCrypt was ended in 5/2014 after Microsoft terminated support of Windows XP. Windows 8/7/Vista and later offer integrated support for encrypted disks and virtual disk images. Such integrated support is also available on other platforms. You should migrate any data encrypted by TrueCrypt to encrypted disks or virtual disk images supported on your platform.
BitLocker Drive Encryption is a data protection feature that integrates with the operating system and addresses the threats of data theft or exposure from lost, stolen, or inappropriately decommissioned computers.
Boxcryptor is an easy-to-use encryption software optimized for the cloud. It allows the secure use of cloud storage services without sacrificing comfort.Discontinued
Boxcryptor has been acquired by Dropbox on November 29, 2022, and is no longer accepting new users. https://www.boxcryptor.com/en/blog/post/boxcryptor-and-dropbox-user-info/
EncFS provides an encrypted filesystem in user-space. It runs without any special permissions and uses the FUSE library and Linux kernel module to provide the filesystem interface. You can find links to source and binary releases below.
The author has agreed that EncFS in its current form is dangerous (to security) for several reasons. Wikipedia has a brief summary: https://en.wikipedia.org/wiki/EncFS#General_Security_ConcernsThe actual audit, which the author participated in, is here: https://defuse.ca/audits/encfs.htm
Platform-independent password-based authenticated encryption of files & folders.