Caesar cipher · shift and solve
Caesar cipher encoder & solver
Julius Caesar shifted each letter three places to hide his messages. Choose any shift to encode your own text, or paste a coded message without knowing the key: the solver tries all 25 shifts and ranks them by how much they look like English, so the answer is usually at the top.
How to use the tool
- 1
Paste the ciphertext
Put the coded message in the input box. Case, spaces and punctuation are kept.
- 2
Check the best guess
The brute-force panel lists every shift and marks the one whose letter counts are closest to English.
- 3
Pick the shift
Tap the row that reads correctly. The tool switches to Decode with that shift.
- 4
Encode a reply
Switch to Encode, set a shift with the slider and type your message. Swap to check it decodes.
QRScanKaro
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Make a clue QR →Frequently asked questions
How does the solver find the right shift?
It decodes the text with each of the 25 shifts and counts how often each letter appears. The version whose counts are closest to normal English, where E, T and A are common and Q and Z are rare, is marked as the best guess.
Why is the best guess sometimes wrong?
Very short messages have too few letters for the counts to mean much, and names or other languages do not follow English patterns. Read down the list; the right answer stands out once you see it.
What shift did Caesar use?
Roman writers say Julius Caesar used a shift of 3, so A became D. His nephew Augustus is said to have used a shift of 1. Any shift from 1 to 25 works the same way.
Is ROT13 a Caesar cipher?
Yes. ROT13 is Caesar with a shift of 13. Because 13 is half of 26, the same shift both encodes and decodes.
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