Caesar Cipher & ROT13
A simple substitution cipher tool. Shift the alphabet to quickly encode or decode secret messages completely offline in your browser.
Input Text
Operation Mode
A shift of 13 is commonly known as ROT13, where encoding and decoding are the exact same operation.
Result (encoded)
Result will appear here...
Alphabet Shift Visualization
What is the Caesar Cipher?
The Caesar cipher is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.
What is ROT13?
ROT13 ("rotate by 13 places") is a special case of the Caesar cipher where the shift is exactly 13. Because the English alphabet has 26 letters, a shift of 13 means that encoding and decoding use the exact same algorithm. It is frequently used in online forums as a means of hiding spoilers, punchlines, puzzle solutions, and offensive materials from the casual glance.