You can directly visit one of the CrypTool topic pages by clicking one of the five buttons here below.
CrypTool 1 (CT1) is an open-source Windows program for cryptography and cryptanalysis. It’s the most wide-spreaded e-learning software of its kind.
CrypTool 2 (CT2) is an open-source program offering an innovative visual programming GUI to experiment with cryptographic procedures and to animate their cascades.
JCrypTool (JCT) is an open-source e-learning platform, allowing to experiment comprehensively with cryptography on Linux, MAC OS X, and Windows.
CrypTool-Online (CTO) runs in a browser and provides a huge variety of encryption methods and analysis tools including many illustrated examples.
MysteryTwister C3 (MTC3) is an international Crypto Cipher Contest offering a broad variety of challenges, a moderated forum and an ongoing hall-of-fame.
...that CrypTool is open source?