Caesar Cipher & ROT13
Encode and decode Caesar cipher text with any shift, including ROT13. Brute-force all 25 keys to crack unknown messages. Free online cipher tool.
Mode
Shift: 13 (ROT13)
Ciphertext
Frequently asked questions
What is ROT13?
A Caesar cipher with a shift of 13. Because the alphabet has 26 letters, applying ROT13 twice returns the original text.
Is a Caesar cipher secure?
No. With only 25 possible keys it can be broken in seconds, as the brute-force list shows. Use it for puzzles and learning, not secrets.
Are numbers and punctuation changed?
No. Only the letters A–Z are shifted; case is preserved.