🏛️Caesar Cipher

Encrypt and decrypt text using the Caesar cipher with custom shift.

Plaintext

Shift Amount3

125

Enter text and adjust the shift to encrypt or decrypt.

About Caesar Cipher

The Caesar Cipher tool encodes or decodes text using the classical Caesar substitution cipher, shifting each letter by a configurable number of positions in the alphabet. Use it to learn the basics of cryptography, solve puzzles, or encode messages with the same cipher used by Julius Caesar.

How to Use Caesar Cipher

1
Enter your message
Type or paste the text you want to encode or decode.
2
Set the shift value
Enter a shift number from 1 to 25. ROT13 is a Caesar cipher with a shift of 13.
3
Encode or decode
Click 'Encrypt' to apply the shift to the plaintext, or 'Decrypt' to reverse the shift and recover the original message.

Common Use Cases

Encoding secret messages for escape rooms or classroom puzzles
Teaching the concept of substitution ciphers in cryptography courses
Decoding Caesar-cipher-encoded puzzles and challenges
Demonstrating why simple ciphers are vulnerable to frequency analysis

Frequently Asked Questions

What is a Caesar cipher?

A Caesar cipher is a simple substitution cipher where each letter in the plaintext is shifted a fixed number of positions down the alphabet. For example, with a shift of 3, 'A' becomes 'D', 'B' becomes 'E', and so on.

How do I decode a Caesar cipher if I don't know the shift?

You can brute-force a Caesar cipher by trying all 25 possible shift values — the tool includes a 'Try All Shifts' mode that shows you every possible decryption so you can identify the one that produces readable text.

Is Caesar cipher secure?

No — with only 25 possible shifts, a Caesar cipher is trivially broken and should not be used for any real security purpose. It is purely an educational and puzzle tool.