Encode or decode text with a shift cipher. Adjust the shift (1–25), use ROT13, and see a live letter mapping.
Built by Garrick Dee · Last verified August 2026
Encrypt, decode, and transform text instantly.
Numbers, names, games and more
Pick Encode to scramble readable text into cipher, or Decode to reverse a message you've received. You can switch between them without re-entering your text.
Drag the slider anywhere from 1 to 25. The alphabet bar below it shows the complete substitution map — every original letter and its cipher equivalent — so you can verify the mapping at a glance before copying.
Copy your result with one click. The Swap button feeds the output back into the input field, useful for applying a second shift on top of the first or quickly confirming a round-trip.
A Caesar cipher is one of the oldest encryption techniques. It shifts every letter in the alphabet by a fixed number of positions. For example, with a shift of 3, A becomes D and Z wraps around to C.
ROT13 is simply a Caesar cipher with a shift of 13. Because the English alphabet has 26 letters, encoding with ROT13 twice returns the original text — it is its own inverse. Click the ROT13 button to set the shift instantly.
Yes. Uppercase letters shift within A–Z and lowercase letters shift within a–z. Digits, spaces, and punctuation are passed through unchanged.
Switch to Decode mode, paste the ciphertext, and set the same shift number that was used when encoding. The original message will appear in the output box immediately.
Yes. After encoding, click Swap to move the output into the input field, change the shift, and encode again. You can chain as many operations as you like.
Caesar cipher was designed for the 26-letter Latin alphabet only. Numbers and punctuation marks have no natural "shifted" equivalent in a 26-position rotation, so this tool leaves them as-is — a period stays a period, "7" stays "7". This is standard behavior across Caesar cipher implementations. If you need digits shifted too, you'd need a different cipher scheme where the character set is explicitly extended beyond A–Z.
Set your shift value using the slider or type a number directly — the range is 1 to 25. Hit ROT13 to jump straight to shift 13, the most common preset. Type your message in the top field and the encoded output appears below in real time. To decode an existing cipher, paste the encoded text into the top field and use Swap to move it to the output — then reverse the shift (e.g. if it was encoded at shift 7, set the slider to 7 and read the top field). Both fields update live as you adjust the shift.