ROT13 is hardly encryption, but it provides a meager level of obfuscation and is simple and quick. I originally wrote an implementation of rot13, but found it annoying that numeric and non-alphabetic characters were unchanged. This tool lets you use either rot13 or rot47, a modified algorithm I wrote to handle alphanumeric and printable characters (including space). Hitting either button will toggle between encrypting and decrypting. All of the work is done in your browser, meaning your text is never sent to the server.