Caesar cipher decoder
Know the shift? Pick it. Otherwise compare every possibility, then copy the result you choose.
For short letter-shift puzzles, not secure encryption. No account needed.
Move A-Z and a-z backward by this many places. A shift of 3 turns D into A.
13 / 1,000 UTF-16 input units. No silent shortening.
Result for shift 3
Every shift starts from your original. Only ASCII letters move; numbers, punctuation and other characters stay in place.
Not sure of the shift?
Compare all 26 possibilities, including unchanged text. Choose a result to put it in the output above, then copy or download. The tool does not guess which one is meaningful.
Actual decoded examples
- Shift 3: PHHW DW QLQH.
- MEET AT NINE.
- Shift 13: Uryyb, jbeyq!
- Hello, world!
- Shift 1: Abc XYZ 9!
- Zab WXY 9!
How to decode a Caesar cipher
Paste the cipher text and choose the shift that was used to move the original letters forward. Decoding moves them backward: with shift 3, D becomes A, E becomes B and A wraps around to X. Uppercase and lowercase stay separate.
If the shift is unknown, open Compare all shifts. Each candidate uses your original input, not the last result. Use shift puts that candidate in the copyable output; it does not replace the original. More than one result can look plausible, especially with very short text.
Shift 0 leaves text unchanged. Shift 13 is ROT13: applying the same shift twice restores the original ASCII letters. Some puzzles describe the shift in the opposite direction; compare all possibilities rather than assuming a different convention is wrong.
What changes, and what does not
Only A-Z and a-z rotate. Digits, punctuation, spaces, tabs, line breaks, emoji and non-ASCII letters remain unchanged. Combining marks stay where they were, so an ASCII base letter with an accent can move while the accent stays attached. The tool does not normalize or transliterate text.
This is not a general cryptogram solver, a custom-alphabet decoder or automatic language detection. Caesar has only 26 shifts here, including the unchanged one; it cannot protect passwords or private messages. Use it for puzzles, not secrets.
For dots and dashes, use the Morse code translator. To inspect unusual characters, open the Unicode inspector. You can paste a decoded puzzle heading into the ASCII banner generator.
Limits, exports and data handling
Up to 1,000 UTF-16 input units. The result has the same length; nothing is silently shortened. Incomplete Unicode, bidirectional formatting controls and controls other than tabs and line breaks are rejected. Browser text fields normally turn pasted CRLF or lone CR endings into LF.
Copy and TXT contain only the selected result, with no shift label or added final newline. TXT uses UTF-8; clipboard and receiving editors may adapt line endings. If copying fails, select the raw result or use TXT.
Your input stays in this page's memory, not links, saved settings or analytics events. Export before leaving. Site resources and analytics still make requests; see data handling.
Background: Caesar cipher and shift conventions.