Caesar Cipher Encoder & Decoder
Encode and decode messages using the Caesar cipher — the shift-3 substitution cipher used by Julius Caesar himself. Each letter is shifted forward 3 positions in the alphabet (A becomes D, B becomes E… Z wraps back to C). Non-letter characters pass through unchanged.
About Caesar Cipher
The Caesar cipher is one of the simplest and most widely known encryption techniques. It is a substitution cipher in which each letter in the plaintext is replaced by a letter a fixed number of positions down the alphabet. Julius Caesar reportedly used it with a shift of 3 to communicate with his generals.
Despite being trivially broken by modern standards, the Caesar cipher introduced the concept of substitution encryption that underlies much of modern cryptography. It is the foundation of the Vigenère cipher, and ROT13 is simply a Caesar cipher with shift 13 (self-inverse because 26÷2=13).
Our tool uses shift 3 (the classical Caesar standard). Encode converts plain text; decode reverses it. Note: the cipher only affects alphabetic characters — spaces, numbers, and punctuation pass through unaltered.