Cipher Encoder & Decoder
Encode and decode text using classic ciphers: ROT13, Caesar cipher with custom shift, Atbash mirror cipher, and Vigenère cipher. Perfect for puzzles, games, and learning cryptography.
ROT13 shifts each letter by 13. Applying it twice returns the original. Numbers and punctuation are unchanged.
Frequently asked
questions
ROT13 (rotate by 13) is a Caesar cipher with a shift of 13. Since the English alphabet has 26 letters, applying ROT13 twice returns the original text. It's identical for encoding and decoding.
The Caesar cipher shifts each letter by a fixed number (e.g., shift 3: A→D, B→E). Julius Caesar reportedly used a shift of 3. It's easily broken but historically significant as one of the first encryption techniques.
The Vigenère cipher uses a keyword to shift each letter by a different amount, making it much harder to crack than Caesar. Each letter of the key determines the shift for the corresponding letter in the plaintext.