OneTime!

[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.

Enigmail is a security extension to Mozilla Thunderbird and SeaMonkey. It enables you to write and receive email messages signed and/or encrypted with the OpenPGP standard.

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.

Gpg4win is an installer package for Windows (2000/XP/2003/Vista) with computer programs and handbooks for email and file encryption. Both relevant cryptography standards are supported, OpenPGP and S/MIME. Gpg4win and the software included with Gpg4win are Free Software (among other things free of charge for all commercial and non-commercial purposes).

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.

FreeOTFE is a free, open source, "on-the-fly" (OTFE) disk encryption program for PCs running MS Windows and Windows Mobile PDAs (FreeOTFE4PDA).

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.

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. »

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

This is a Java-based application that allows the user to important files that are on that operating system to encrypt easy and secure and organize.Tested on WinXP, Win7 & OS X 10.6