rot13 tool
Rot13 is a very rudimentary tool to obfuscate text. With this online tool, you can convert rot13 text (encrypt or decrypt). Possibly the world's most basic cipher, rot13 encrypts text by rotating the alphabet by 13 letters, and hence the name, rot13. One handy feature of rot13 is that when you use a tool such as this online rot13 converter you can use the same technique to decrypt the text as to encrypt it in the first place... In other words, the tool does not need to know if you are encrypting or decrypting, it performs the same function, regardless.
You may note, that rot13 is so basic, that it doesn't even try to encrypt numerals... text only. If you are trying to keep information private from sophisticated people or organizations, rot13 is not the proper tool for the job. In this day and age, it's primary use might be to keep search-engines from indexing it for what it really is, or to discuss movies, books, or video-games in a public forum without giving away the plot to anyone, by doing a rot13 on any information that might be considered a "spoiler".
If you want a robust tool to encrypt any type of text or computer file, I recommend PGP or it's free cousin GnuPG. Go ahead, put the term of your choice into Google, or your favorite search-engine, and check it out... it's a very powerful too for maintaining your privacy and security.