Notae Caesaris
Caesar Cipher
Shift your letters the way Caesar shifted his dispatches.
Suetonius records that Julius Caesar enciphered messages by shifting each letter three places. Enter text, pick a shift, encode or decode. Try ROT13 or reveal all 25 shifts at once.
Suetonius records that Caesar wrote to his generals by shifting each letter three places — the first cipher a Roman ever needed.
Related tools
How to use
- Paste or type the text to encipher or decipher.
- Set the shift (1–25) or use ROT13 / Caesar +3 presets.
- Choose encode or decode. Use "all shifts" to brute-force unknown messages.
FAQ
- How does the Caesar cipher work?
- Each letter is replaced by the letter N positions later in the alphabet. Decoding shifts backward by the same amount. Only A–Z and a–z are transformed; numbers and punctuation stay unchanged.
- What is ROT13?
- ROT13 is a Caesar cipher with shift 13. Because the Latin alphabet has 26 letters, applying ROT13 twice returns the original text.
- Is this secure?
- No. The Caesar cipher is a teaching tool and a puzzle, not encryption. A child with a stick could break it. Use a password manager for real secrets.