Encode / Decode
Below you will find two tools, one that explains graphically what a shift cipher does and what it looks like, and another that goes through all rotations possible to quickly check if a cipher is a shift cipher. They both can use custom alphabets by using the options.
A multi alphabetic shift cipher tool
A graphical tool to demonstrate a simple shift cipher. Click on a letter set to add it to your input/output.
Shift cipher quick check tool
This is a tool to check if any ciphertext is a shift cipher by printing out all possible rotations and presenting them back.
Obviously it will also convert any text you enter into its rotated equivalent.
Common options are ROT13, a 13 shifted cipher, being half of the letters of the alphabet. Then there is ROT47 which uses uses all the characters of the ASCII set letting you encipher URLs and some other characters. And ROT5, that will encode only numbers.