Caesar Cipher
Caesar decryption tool
Note: All operations occur locally in your browser.
Input + output
Shift letters backward by this amount (0–25).
CaesarDecrypt
Caesar Decryption Online
Use this tool to reverse a Caesar cipher by shifting letters back by a fixed amount. If the shift is unknown, try common values like 1–5 or 13 to check for readable text.
Common Cases
- ROT13: A shift of 13 used in puzzles and forums.
- Short messages: Try a few shifts and look for readable output.
Try All Shifts
If the shift is unknown, use “Try All Shifts” to view every possible decryption from 0–25 and pick the readable result. This is a standard way to break a Caesar cipher because there are only 26 possibilities.
How to Decrypt a Caesar Cipher
- Enter the encrypted text.
- Set the shift value that was used to encrypt.
- Click “Decrypt” to recover the original message.
Example
Ciphertext: dwwdfn dw gdzq with shift 3 becomes attack at dawn.
Caesar Cipher Notes
- Only letters are shifted; numbers and symbols stay the same.
- Case is preserved.
- For stronger security, use modern encryption tools.