This is an HTML & JavaScript based tool for solving simple substitution ciphers. In a simple substitution cipher each letter is replaced with another. ROT13 and Caesar ciphers are special cases of substitution ciphers where the alphabet is just shifted (by 13 and 3 places, respectively) but not shuffled in any other way. Using this tool it is easy to try various substitution alphabets and to see the resulting plaintext immediately. This tool does not support solving Vigenère ciphers or any other polyalphabetic ciphers.
You should be able to test this tool right away here and to run the test suite for this project here.
The following external libraries are used: