Encode
Choose Encode, set the shift, then enter the plain message. The tool applies that shift to every letter.
Caesar cipher
Encode or decode a message with an exact alphabet shift.
Codes
Choose a shift from 1 to 25 to encode or decode text with the Caesar cipher. The shifted alphabet updates automatically.
Settings
Conversion direction
Alphabet used
Plain alphabetABCDEFGHIJKLMNOPQRSTUVWXYZ
Shifted alphabetDEFGHIJKLMNOPQRSTUVWXYZABC
Source text
0 source char.
Result
Add source text.
Quick explanation
Enter text, choose encode or decode, then adjust the shift. Letters move through the alphabet while spaces, digits, and punctuation stay visible.
Try this too
Unknown shift?
Use the automatic Caesar decoder to test all 25 shifts and find the readable sentence.
Additional information
Understanding the Caesar cipher
The Caesar cipher shifts every letter by a fixed number of positions in the alphabet. With a shift of 3, A becomes D, B becomes E, and Z wraps around to C.
Decode
Choose Decode with the same shift to recover the original text. If you do not know the shift, use the automatic decoder.
Puzzles and hunts
Caesar is a classic puzzle cipher: it is quick to test, easy to explain, and often used as a first layer.
Example with a shift of 3
| Plain alphabet | A | B | C | D | E |
|---|---|---|---|---|---|
| Shifted alphabet | D | E | F | G | H |
| Example | APP becomes DSS. | ||||
Compared with ROT13
ROT13 is a special Caesar cipher with a fixed shift of 13.
When the shift changes
If the shift depends on a keyword, use the Vigenère cipher or Keyword shift.
Learn more
See also the Wikipedia article about the Caesar cipher.
Special case: ROT13
ROT13 is a Caesar cipher with a fixed shift of 13. It is useful when a puzzle explicitly says ROT13 or when you want to lightly hide an answer.
Limits and reuse
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