Caesar Cipher
Shift letters by any amount 0–25. Pick 13 for ROT13.
CipherShiftClient-sideFree to use
Shift3
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How to use
- Paste your text. Preserves case and non-letter chars.
- Pick a shift. 0 to 25.
- Use a negative shift. To decode, use the inverse shift.
Common use cases
- Learning classical cryptography
- Puzzle making
- Casual text obfuscation
Frequently asked questions
- What is the Caesar cipher best used for?
- The Caesar cipher is a teaching tool and a recreational puzzle aid, not a security mechanism. It is useful for introducing students to substitution ciphers, setting up escape-room style puzzles, or adding light obfuscation to text where actual secrecy is not required.
- How does the shift work?
- Each letter is moved forward in the alphabet by the shift amount, wrapping around from Z to A. A shift of 1 turns A into B, Z into A, and so on. Only the 26 letters a-z and A-Z are shifted; digits, punctuation, and spaces pass through unchanged, and letter case is preserved.
- Does this tool send my text to a server?
- No. The transformation runs entirely in your browser. Nothing you type is transmitted to any server.
- How do I decode a Caesar-ciphered message?
- To reverse a shift of N, apply a shift of 26 minus N. For example, if the message was encoded with shift 3, decode it with shift 23. Alternatively, if you do not know the shift, you can try all 25 non-trivial shifts; with only 25 options, a human can spot readable English in seconds.
- What is the difference between this tool and ROT13?
- ROT13 is simply the Caesar cipher with a fixed shift of 13. Because 13 is exactly half of 26, ROT13 is its own inverse: encoding and decoding use the same operation. The Caesar cipher tool lets you choose any shift from 0 to 25, giving you ROT13 as one of 26 possible settings.
- Does the tool work with accented letters or non-Latin scripts?
- No. Only the 26 standard ASCII letters (a-z, A-Z) are shifted. Accented characters like é or ñ, Cyrillic, Greek, and all other non-ASCII text pass through without modification. The cipher is defined only over the Latin alphabet.
Related tools
How to use
- Paste your text. Preserves case and non-letter chars.
- Pick a shift. 0 to 25.
- Use a negative shift. To decode, use the inverse shift.
Common use cases
- Learning classical cryptography
- Puzzle making
- Casual text obfuscation
Frequently asked questions
- What is the Caesar cipher best used for?
- The Caesar cipher is a teaching tool and a recreational puzzle aid, not a security mechanism. It is useful for introducing students to substitution ciphers, setting up escape-room style puzzles, or adding light obfuscation to text where actual secrecy is not required.
- How does the shift work?
- Each letter is moved forward in the alphabet by the shift amount, wrapping around from Z to A. A shift of 1 turns A into B, Z into A, and so on. Only the 26 letters a-z and A-Z are shifted; digits, punctuation, and spaces pass through unchanged, and letter case is preserved.
- Does this tool send my text to a server?
- No. The transformation runs entirely in your browser. Nothing you type is transmitted to any server.
- How do I decode a Caesar-ciphered message?
- To reverse a shift of N, apply a shift of 26 minus N. For example, if the message was encoded with shift 3, decode it with shift 23. Alternatively, if you do not know the shift, you can try all 25 non-trivial shifts; with only 25 options, a human can spot readable English in seconds.
- What is the difference between this tool and ROT13?
- ROT13 is simply the Caesar cipher with a fixed shift of 13. Because 13 is exactly half of 26, ROT13 is its own inverse: encoding and decoding use the same operation. The Caesar cipher tool lets you choose any shift from 0 to 25, giving you ROT13 as one of 26 possible settings.
- Does the tool work with accented letters or non-Latin scripts?
- No. Only the 26 standard ASCII letters (a-z, A-Z) are shifted. Accented characters like é or ñ, Cyrillic, Greek, and all other non-ASCII text pass through without modification. The cipher is defined only over the Latin alphabet.