Steadycrypt!

[TrueCrypt is not exactly "Open Source", but the source is available. See the reviews to get more information.]

GnuPG allows to encrypt and sign your data and communication, features a versatile key management system as well as access modules for all kinds of public key directories. GnuPG, also known as GPG, is a command line tool with features for easy integration with other applications. A wealth of frontend applications and libraries are available. Version 2 of GnuPG also provides support for S/MIME.

AxCrypt is a simple file encryption software for Windows. It integrates seamlessly with your workflow to encrypt, decrypt, store, send and work with files.

AES Crypt is an advanced file encryption utility that integrates with the Windows shell or runs from the Linux command prompt to provide a simple, yet powerful, tool for encrypting files using the Advanced Encryption Standard (AES). A Java library is also available for developers using Java to read and write AES formatted files.

LibreCrypt (formerly DoxBox) is an open-source disk encryption for Windows and the successor of FreeOTFE

GPG for Mailis an open source plugin for Apple Mail. Encrypt, decrypt, sign and verify mails using OpenPGP with a few simple clicks.

If your computer were ever to be stolen, are you certain that your personal information cannot be discovered? Jetico’s BestCrypt software automatically encrypts your files so that nobody can read the data unless they have the right password or keys.

DCrypt is an encryption and decryption tool that combines in a smart way multiple algorithms. The combination of multiple strong algorithms makes it much more difficult for hackers to get the plain content of the encrypted file without the password.

The Gostcrypt project has been launched at the end of 2013 as fork of the (late) Truecrypt project.

ProxyCrypt is a command line tool that creates encrypted volumes within a file or a hard drive.It works as a "proxy" for the ImDisk Virtual Disk Driver .

Drag'n'Crypt ULTRA is a small, coding program assistance whose you confidential data which can be served very simply against the access of unauthorized ones protect can. You draw the file (EN), which can be coded, simply on the program window (the drop zone) and DCU codes the file (EN) with the very safe Twofish coding algorithm. Decoding succeeds just as fast and simply in the same way. Drag'n'Crypt ULTRA is Freeware thus perfectly free of charge and. DCU does not contain any Adware or Spyware. »

Securely encrypt your private and confidential files or whole folders.The encryption/decryption process is simply done by dragging the selected file(s) or folders(s) to application window.Files are encrypted using strong encryption algorithm: AES (Rijndael) 256bit, RC6 256bit, Serpent 256bit, Blowfish 448bit, Twofish 256bit, GOST 256bit + (Threefish 1024bit and SHACAL-2 512bit for Pro Version) ciphers are available.Cross-Platform (Windows, Linux, Mac OS X, ...) GUI Version and Command Line Version are available.Compatible with the Secret Space Encryptor for Android.A wide range of compatible platforms (desktop and mobile) allow easy sharing of protected data.Easy to use. »